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1547 lines
50 KiB
Python
1547 lines
50 KiB
Python
# Copyright (C) 2003-2005 Peter J. Verveer
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following
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# disclaimer in the documentation and/or other materials provided
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# with the distribution.
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#
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# 3. The name of the author may not be used to endorse or promote
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# products derived from this software without specific prior
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# written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import numpy
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import numpy as np
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from . import _ni_support
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from . import _ni_label
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from . import _nd_image
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from . import morphology
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__all__ = ['label', 'find_objects', 'labeled_comprehension', 'sum', 'mean',
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'variance', 'standard_deviation', 'minimum', 'maximum', 'median',
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'minimum_position', 'maximum_position', 'extrema', 'center_of_mass',
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'histogram', 'watershed_ift', 'sum_labels']
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def label(input, structure=None, output=None):
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"""
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Label features in an array.
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Parameters
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----------
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input : array_like
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An array-like object to be labeled. Any non-zero values in `input` are
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counted as features and zero values are considered the background.
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structure : array_like, optional
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A structuring element that defines feature connections.
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`structure` must be centrosymmetric
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(see Notes).
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If no structuring element is provided,
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one is automatically generated with a squared connectivity equal to
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one. That is, for a 2-D `input` array, the default structuring element
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is::
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[[0,1,0],
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[1,1,1],
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[0,1,0]]
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output : (None, data-type, array_like), optional
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If `output` is a data type, it specifies the type of the resulting
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labeled feature array.
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If `output` is an array-like object, then `output` will be updated
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with the labeled features from this function. This function can
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operate in-place, by passing output=input.
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Note that the output must be able to store the largest label, or this
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function will raise an Exception.
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Returns
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-------
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label : ndarray or int
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An integer ndarray where each unique feature in `input` has a unique
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label in the returned array.
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num_features : int
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How many objects were found.
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If `output` is None, this function returns a tuple of
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(`labeled_array`, `num_features`).
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If `output` is a ndarray, then it will be updated with values in
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`labeled_array` and only `num_features` will be returned by this
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function.
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See Also
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--------
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find_objects : generate a list of slices for the labeled features (or
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objects); useful for finding features' position or
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dimensions
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Notes
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-----
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A centrosymmetric matrix is a matrix that is symmetric about the center.
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See [1]_ for more information.
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The `structure` matrix must be centrosymmetric to ensure
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two-way connections.
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For instance, if the `structure` matrix is not centrosymmetric
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and is defined as::
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[[0,1,0],
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[1,1,0],
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[0,0,0]]
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and the `input` is::
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[[1,2],
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[0,3]]
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then the structure matrix would indicate the
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entry 2 in the input is connected to 1,
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but 1 is not connected to 2.
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Examples
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--------
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Create an image with some features, then label it using the default
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(cross-shaped) structuring element:
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>>> from scipy.ndimage import label, generate_binary_structure
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>>> a = np.array([[0,0,1,1,0,0],
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... [0,0,0,1,0,0],
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... [1,1,0,0,1,0],
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... [0,0,0,1,0,0]])
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>>> labeled_array, num_features = label(a)
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Each of the 4 features are labeled with a different integer:
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>>> num_features
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4
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>>> labeled_array
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array([[0, 0, 1, 1, 0, 0],
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[0, 0, 0, 1, 0, 0],
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[2, 2, 0, 0, 3, 0],
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[0, 0, 0, 4, 0, 0]])
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Generate a structuring element that will consider features connected even
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if they touch diagonally:
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>>> s = generate_binary_structure(2,2)
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or,
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>>> s = [[1,1,1],
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... [1,1,1],
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... [1,1,1]]
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Label the image using the new structuring element:
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>>> labeled_array, num_features = label(a, structure=s)
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Show the 2 labeled features (note that features 1, 3, and 4 from above are
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now considered a single feature):
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>>> num_features
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2
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>>> labeled_array
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array([[0, 0, 1, 1, 0, 0],
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[0, 0, 0, 1, 0, 0],
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[2, 2, 0, 0, 1, 0],
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[0, 0, 0, 1, 0, 0]])
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References
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----------
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.. [1] James R. Weaver, "Centrosymmetric (cross-symmetric)
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matrices, their basic properties, eigenvalues, and
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eigenvectors." The American Mathematical Monthly 92.10
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(1985): 711-717.
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"""
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input = numpy.asarray(input)
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if numpy.iscomplexobj(input):
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raise TypeError('Complex type not supported')
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if structure is None:
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structure = morphology.generate_binary_structure(input.ndim, 1)
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structure = numpy.asarray(structure, dtype=bool)
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if structure.ndim != input.ndim:
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raise RuntimeError('structure and input must have equal rank')
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for ii in structure.shape:
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if ii != 3:
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raise ValueError('structure dimensions must be equal to 3')
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# Use 32 bits if it's large enough for this image.
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# _ni_label.label() needs two entries for background and
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# foreground tracking
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need_64bits = input.size >= (2**31 - 2)
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if isinstance(output, numpy.ndarray):
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if output.shape != input.shape:
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raise ValueError("output shape not correct")
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caller_provided_output = True
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else:
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caller_provided_output = False
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if output is None:
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output = np.empty(input.shape, np.intp if need_64bits else np.int32)
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else:
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output = np.empty(input.shape, output)
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# handle scalars, 0-D arrays
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if input.ndim == 0 or input.size == 0:
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if input.ndim == 0:
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# scalar
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maxlabel = 1 if (input != 0) else 0
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output[...] = maxlabel
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else:
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# 0-D
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maxlabel = 0
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if caller_provided_output:
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return maxlabel
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else:
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return output, maxlabel
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try:
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max_label = _ni_label._label(input, structure, output)
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except _ni_label.NeedMoreBits as e:
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# Make another attempt with enough bits, then try to cast to the
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# new type.
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tmp_output = np.empty(input.shape, np.intp if need_64bits else np.int32)
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max_label = _ni_label._label(input, structure, tmp_output)
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output[...] = tmp_output[...]
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if not np.all(output == tmp_output):
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# refuse to return bad results
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raise RuntimeError(
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"insufficient bit-depth in requested output type"
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) from e
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if caller_provided_output:
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# result was written in-place
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return max_label
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else:
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return output, max_label
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def find_objects(input, max_label=0):
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"""
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Find objects in a labeled array.
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Parameters
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----------
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input : ndarray of ints
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Array containing objects defined by different labels. Labels with
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value 0 are ignored.
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max_label : int, optional
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Maximum label to be searched for in `input`. If max_label is not
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given, the positions of all objects are returned.
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Returns
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-------
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object_slices : list of tuples
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A list of tuples, with each tuple containing N slices (with N the
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dimension of the input array). Slices correspond to the minimal
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parallelepiped that contains the object. If a number is missing,
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None is returned instead of a slice.
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See Also
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--------
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label, center_of_mass
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Notes
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-----
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This function is very useful for isolating a volume of interest inside
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a 3-D array, that cannot be "seen through".
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Examples
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--------
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>>> from scipy import ndimage
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>>> a = np.zeros((6,6), dtype=int)
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>>> a[2:4, 2:4] = 1
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>>> a[4, 4] = 1
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>>> a[:2, :3] = 2
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>>> a[0, 5] = 3
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>>> a
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array([[2, 2, 2, 0, 0, 3],
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[2, 2, 2, 0, 0, 0],
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[0, 0, 1, 1, 0, 0],
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[0, 0, 1, 1, 0, 0],
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[0, 0, 0, 0, 1, 0],
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[0, 0, 0, 0, 0, 0]])
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>>> ndimage.find_objects(a)
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[(slice(2, 5, None), slice(2, 5, None)), (slice(0, 2, None), slice(0, 3, None)), (slice(0, 1, None), slice(5, 6, None))]
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>>> ndimage.find_objects(a, max_label=2)
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[(slice(2, 5, None), slice(2, 5, None)), (slice(0, 2, None), slice(0, 3, None))]
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>>> ndimage.find_objects(a == 1, max_label=2)
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[(slice(2, 5, None), slice(2, 5, None)), None]
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>>> loc = ndimage.find_objects(a)[0]
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>>> a[loc]
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array([[1, 1, 0],
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[1, 1, 0],
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[0, 0, 1]])
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"""
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input = numpy.asarray(input)
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if numpy.iscomplexobj(input):
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raise TypeError('Complex type not supported')
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if max_label < 1:
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max_label = input.max()
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return _nd_image.find_objects(input, max_label)
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def labeled_comprehension(input, labels, index, func, out_dtype, default, pass_positions=False):
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"""
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Roughly equivalent to [func(input[labels == i]) for i in index].
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Sequentially applies an arbitrary function (that works on array_like input)
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to subsets of an N-D image array specified by `labels` and `index`.
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The option exists to provide the function with positional parameters as the
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second argument.
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Parameters
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----------
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input : array_like
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Data from which to select `labels` to process.
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labels : array_like or None
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Labels to objects in `input`.
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If not None, array must be same shape as `input`.
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If None, `func` is applied to raveled `input`.
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index : int, sequence of ints or None
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Subset of `labels` to which to apply `func`.
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If a scalar, a single value is returned.
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If None, `func` is applied to all non-zero values of `labels`.
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func : callable
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Python function to apply to `labels` from `input`.
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out_dtype : dtype
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Dtype to use for `result`.
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default : int, float or None
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Default return value when a element of `index` does not exist
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in `labels`.
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pass_positions : bool, optional
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If True, pass linear indices to `func` as a second argument.
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Default is False.
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Returns
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-------
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result : ndarray
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Result of applying `func` to each of `labels` to `input` in `index`.
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Examples
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--------
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>>> a = np.array([[1, 2, 0, 0],
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... [5, 3, 0, 4],
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... [0, 0, 0, 7],
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... [9, 3, 0, 0]])
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>>> from scipy import ndimage
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>>> lbl, nlbl = ndimage.label(a)
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>>> lbls = np.arange(1, nlbl+1)
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>>> ndimage.labeled_comprehension(a, lbl, lbls, np.mean, float, 0)
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array([ 2.75, 5.5 , 6. ])
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Falling back to `default`:
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>>> lbls = np.arange(1, nlbl+2)
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>>> ndimage.labeled_comprehension(a, lbl, lbls, np.mean, float, -1)
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array([ 2.75, 5.5 , 6. , -1. ])
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Passing positions:
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>>> def fn(val, pos):
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... print("fn says: %s : %s" % (val, pos))
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... return (val.sum()) if (pos.sum() % 2 == 0) else (-val.sum())
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...
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>>> ndimage.labeled_comprehension(a, lbl, lbls, fn, float, 0, True)
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fn says: [1 2 5 3] : [0 1 4 5]
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fn says: [4 7] : [ 7 11]
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fn says: [9 3] : [12 13]
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array([ 11., 11., -12., 0.])
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"""
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as_scalar = numpy.isscalar(index)
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input = numpy.asarray(input)
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if pass_positions:
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positions = numpy.arange(input.size).reshape(input.shape)
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if labels is None:
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if index is not None:
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raise ValueError("index without defined labels")
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if not pass_positions:
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return func(input.ravel())
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else:
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return func(input.ravel(), positions.ravel())
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try:
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input, labels = numpy.broadcast_arrays(input, labels)
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except ValueError as e:
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raise ValueError("input and labels must have the same shape "
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"(excepting dimensions with width 1)") from e
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if index is None:
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if not pass_positions:
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return func(input[labels > 0])
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else:
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return func(input[labels > 0], positions[labels > 0])
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index = numpy.atleast_1d(index)
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if np.any(index.astype(labels.dtype).astype(index.dtype) != index):
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raise ValueError("Cannot convert index values from <%s> to <%s> "
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"(labels' type) without loss of precision" %
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(index.dtype, labels.dtype))
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index = index.astype(labels.dtype)
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# optimization: find min/max in index, and select those parts of labels, input, and positions
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lo = index.min()
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hi = index.max()
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mask = (labels >= lo) & (labels <= hi)
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# this also ravels the arrays
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labels = labels[mask]
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input = input[mask]
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if pass_positions:
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positions = positions[mask]
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# sort everything by labels
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label_order = labels.argsort()
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labels = labels[label_order]
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input = input[label_order]
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if pass_positions:
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positions = positions[label_order]
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index_order = index.argsort()
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sorted_index = index[index_order]
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def do_map(inputs, output):
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"""labels must be sorted"""
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nidx = sorted_index.size
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# Find boundaries for each stretch of constant labels
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# This could be faster, but we already paid N log N to sort labels.
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lo = numpy.searchsorted(labels, sorted_index, side='left')
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hi = numpy.searchsorted(labels, sorted_index, side='right')
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for i, l, h in zip(range(nidx), lo, hi):
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if l == h:
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continue
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output[i] = func(*[inp[l:h] for inp in inputs])
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temp = numpy.empty(index.shape, out_dtype)
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temp[:] = default
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if not pass_positions:
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do_map([input], temp)
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else:
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do_map([input, positions], temp)
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output = numpy.zeros(index.shape, out_dtype)
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output[index_order] = temp
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if as_scalar:
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output = output[0]
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return output
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def _safely_castable_to_int(dt):
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"""Test whether the NumPy data type `dt` can be safely cast to an int."""
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int_size = np.dtype(int).itemsize
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safe = ((np.issubdtype(dt, np.signedinteger) and dt.itemsize <= int_size) or
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(np.issubdtype(dt, np.unsignedinteger) and dt.itemsize < int_size))
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return safe
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def _stats(input, labels=None, index=None, centered=False):
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"""Count, sum, and optionally compute (sum - centre)^2 of input by label
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Parameters
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----------
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input : array_like, N-D
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The input data to be analyzed.
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labels : array_like (N-D), optional
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The labels of the data in `input`. This array must be broadcast
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compatible with `input`; typically, it is the same shape as `input`.
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If `labels` is None, all nonzero values in `input` are treated as
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the single labeled group.
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index : label or sequence of labels, optional
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These are the labels of the groups for which the stats are computed.
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If `index` is None, the stats are computed for the single group where
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`labels` is greater than 0.
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centered : bool, optional
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If True, the centered sum of squares for each labeled group is
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also returned. Default is False.
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Returns
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-------
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counts : int or ndarray of ints
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The number of elements in each labeled group.
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sums : scalar or ndarray of scalars
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The sums of the values in each labeled group.
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sums_c : scalar or ndarray of scalars, optional
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The sums of mean-centered squares of the values in each labeled group.
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This is only returned if `centered` is True.
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"""
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def single_group(vals):
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if centered:
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vals_c = vals - vals.mean()
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return vals.size, vals.sum(), (vals_c * vals_c.conjugate()).sum()
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else:
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return vals.size, vals.sum()
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if labels is None:
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return single_group(input)
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|
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# ensure input and labels match sizes
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input, labels = numpy.broadcast_arrays(input, labels)
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|
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if index is None:
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return single_group(input[labels > 0])
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|
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if numpy.isscalar(index):
|
|
return single_group(input[labels == index])
|
|
|
|
def _sum_centered(labels):
|
|
# `labels` is expected to be an ndarray with the same shape as `input`.
|
|
# It must contain the label indices (which are not necessarily the labels
|
|
# themselves).
|
|
means = sums / counts
|
|
centered_input = input - means[labels]
|
|
# bincount expects 1-D inputs, so we ravel the arguments.
|
|
bc = numpy.bincount(labels.ravel(),
|
|
weights=(centered_input *
|
|
centered_input.conjugate()).ravel())
|
|
return bc
|
|
|
|
# Remap labels to unique integers if necessary, or if the largest
|
|
# label is larger than the number of values.
|
|
|
|
if (not _safely_castable_to_int(labels.dtype) or
|
|
labels.min() < 0 or labels.max() > labels.size):
|
|
# Use numpy.unique to generate the label indices. `new_labels` will
|
|
# be 1-D, but it should be interpreted as the flattened N-D array of
|
|
# label indices.
|
|
unique_labels, new_labels = numpy.unique(labels, return_inverse=True)
|
|
counts = numpy.bincount(new_labels)
|
|
sums = numpy.bincount(new_labels, weights=input.ravel())
|
|
if centered:
|
|
# Compute the sum of the mean-centered squares.
|
|
# We must reshape new_labels to the N-D shape of `input` before
|
|
# passing it _sum_centered.
|
|
sums_c = _sum_centered(new_labels.reshape(labels.shape))
|
|
idxs = numpy.searchsorted(unique_labels, index)
|
|
# make all of idxs valid
|
|
idxs[idxs >= unique_labels.size] = 0
|
|
found = (unique_labels[idxs] == index)
|
|
else:
|
|
# labels are an integer type allowed by bincount, and there aren't too
|
|
# many, so call bincount directly.
|
|
counts = numpy.bincount(labels.ravel())
|
|
sums = numpy.bincount(labels.ravel(), weights=input.ravel())
|
|
if centered:
|
|
sums_c = _sum_centered(labels)
|
|
# make sure all index values are valid
|
|
idxs = numpy.asanyarray(index, numpy.int_).copy()
|
|
found = (idxs >= 0) & (idxs < counts.size)
|
|
idxs[~found] = 0
|
|
|
|
counts = counts[idxs]
|
|
counts[~found] = 0
|
|
sums = sums[idxs]
|
|
sums[~found] = 0
|
|
|
|
if not centered:
|
|
return (counts, sums)
|
|
else:
|
|
sums_c = sums_c[idxs]
|
|
sums_c[~found] = 0
|
|
return (counts, sums, sums_c)
|
|
|
|
|
|
def sum(input, labels=None, index=None):
|
|
"""
|
|
Calculate the sum of the values of the array.
|
|
|
|
Notes
|
|
-----
|
|
This is an alias for `ndimage.sum_labels` kept for backwards compatibility
|
|
reasons, for new code please prefer `sum_labels`. See the `sum_labels`
|
|
docstring for more details.
|
|
|
|
"""
|
|
return sum_labels(input, labels, index)
|
|
|
|
|
|
def sum_labels(input, labels=None, index=None):
|
|
"""
|
|
Calculate the sum of the values of the array.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Values of `input` inside the regions defined by `labels`
|
|
are summed together.
|
|
labels : array_like of ints, optional
|
|
Assign labels to the values of the array. Has to have the same shape as
|
|
`input`.
|
|
index : array_like, optional
|
|
A single label number or a sequence of label numbers of
|
|
the objects to be measured.
|
|
|
|
Returns
|
|
-------
|
|
sum : ndarray or scalar
|
|
An array of the sums of values of `input` inside the regions defined
|
|
by `labels` with the same shape as `index`. If 'index' is None or scalar,
|
|
a scalar is returned.
|
|
|
|
See also
|
|
--------
|
|
mean, median
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy import ndimage
|
|
>>> input = [0,1,2,3]
|
|
>>> labels = [1,1,2,2]
|
|
>>> ndimage.sum(input, labels, index=[1,2])
|
|
[1.0, 5.0]
|
|
>>> ndimage.sum(input, labels, index=1)
|
|
1
|
|
>>> ndimage.sum(input, labels)
|
|
6
|
|
|
|
|
|
"""
|
|
count, sum = _stats(input, labels, index)
|
|
return sum
|
|
|
|
|
|
def mean(input, labels=None, index=None):
|
|
"""
|
|
Calculate the mean of the values of an array at labels.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array on which to compute the mean of elements over distinct
|
|
regions.
|
|
labels : array_like, optional
|
|
Array of labels of same shape, or broadcastable to the same shape as
|
|
`input`. All elements sharing the same label form one region over
|
|
which the mean of the elements is computed.
|
|
index : int or sequence of ints, optional
|
|
Labels of the objects over which the mean is to be computed.
|
|
Default is None, in which case the mean for all values where label is
|
|
greater than 0 is calculated.
|
|
|
|
Returns
|
|
-------
|
|
out : list
|
|
Sequence of same length as `index`, with the mean of the different
|
|
regions labeled by the labels in `index`.
|
|
|
|
See also
|
|
--------
|
|
variance, standard_deviation, minimum, maximum, sum, label
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy import ndimage
|
|
>>> a = np.arange(25).reshape((5,5))
|
|
>>> labels = np.zeros_like(a)
|
|
>>> labels[3:5,3:5] = 1
|
|
>>> index = np.unique(labels)
|
|
>>> labels
|
|
array([[0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 0],
|
|
[0, 0, 0, 1, 1],
|
|
[0, 0, 0, 1, 1]])
|
|
>>> index
|
|
array([0, 1])
|
|
>>> ndimage.mean(a, labels=labels, index=index)
|
|
[10.285714285714286, 21.0]
|
|
|
|
"""
|
|
|
|
count, sum = _stats(input, labels, index)
|
|
return sum / numpy.asanyarray(count).astype(numpy.float64)
|
|
|
|
|
|
def variance(input, labels=None, index=None):
|
|
"""
|
|
Calculate the variance of the values of an N-D image array, optionally at
|
|
specified sub-regions.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Nd-image data to process.
|
|
labels : array_like, optional
|
|
Labels defining sub-regions in `input`.
|
|
If not None, must be same shape as `input`.
|
|
index : int or sequence of ints, optional
|
|
`labels` to include in output. If None (default), all values where
|
|
`labels` is non-zero are used.
|
|
|
|
Returns
|
|
-------
|
|
variance : float or ndarray
|
|
Values of variance, for each sub-region if `labels` and `index` are
|
|
specified.
|
|
|
|
See Also
|
|
--------
|
|
label, standard_deviation, maximum, minimum, extrema
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.variance(a)
|
|
7.609375
|
|
|
|
Features to process can be specified using `labels` and `index`:
|
|
|
|
>>> lbl, nlbl = ndimage.label(a)
|
|
>>> ndimage.variance(a, lbl, index=np.arange(1, nlbl+1))
|
|
array([ 2.1875, 2.25 , 9. ])
|
|
|
|
If no index is given, all non-zero `labels` are processed:
|
|
|
|
>>> ndimage.variance(a, lbl)
|
|
6.1875
|
|
|
|
"""
|
|
count, sum, sum_c_sq = _stats(input, labels, index, centered=True)
|
|
return sum_c_sq / np.asanyarray(count).astype(float)
|
|
|
|
|
|
def standard_deviation(input, labels=None, index=None):
|
|
"""
|
|
Calculate the standard deviation of the values of an N-D image array,
|
|
optionally at specified sub-regions.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
N-D image data to process.
|
|
labels : array_like, optional
|
|
Labels to identify sub-regions in `input`.
|
|
If not None, must be same shape as `input`.
|
|
index : int or sequence of ints, optional
|
|
`labels` to include in output. If None (default), all values where
|
|
`labels` is non-zero are used.
|
|
|
|
Returns
|
|
-------
|
|
standard_deviation : float or ndarray
|
|
Values of standard deviation, for each sub-region if `labels` and
|
|
`index` are specified.
|
|
|
|
See Also
|
|
--------
|
|
label, variance, maximum, minimum, extrema
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.standard_deviation(a)
|
|
2.7585095613392387
|
|
|
|
Features to process can be specified using `labels` and `index`:
|
|
|
|
>>> lbl, nlbl = ndimage.label(a)
|
|
>>> ndimage.standard_deviation(a, lbl, index=np.arange(1, nlbl+1))
|
|
array([ 1.479, 1.5 , 3. ])
|
|
|
|
If no index is given, non-zero `labels` are processed:
|
|
|
|
>>> ndimage.standard_deviation(a, lbl)
|
|
2.4874685927665499
|
|
|
|
"""
|
|
return numpy.sqrt(variance(input, labels, index))
|
|
|
|
|
|
def _select(input, labels=None, index=None, find_min=False, find_max=False,
|
|
find_min_positions=False, find_max_positions=False,
|
|
find_median=False):
|
|
"""Returns min, max, or both, plus their positions (if requested), and
|
|
median."""
|
|
|
|
input = numpy.asanyarray(input)
|
|
|
|
find_positions = find_min_positions or find_max_positions
|
|
positions = None
|
|
if find_positions:
|
|
positions = numpy.arange(input.size).reshape(input.shape)
|
|
|
|
def single_group(vals, positions):
|
|
result = []
|
|
if find_min:
|
|
result += [vals.min()]
|
|
if find_min_positions:
|
|
result += [positions[vals == vals.min()][0]]
|
|
if find_max:
|
|
result += [vals.max()]
|
|
if find_max_positions:
|
|
result += [positions[vals == vals.max()][0]]
|
|
if find_median:
|
|
result += [numpy.median(vals)]
|
|
return result
|
|
|
|
if labels is None:
|
|
return single_group(input, positions)
|
|
|
|
# ensure input and labels match sizes
|
|
input, labels = numpy.broadcast_arrays(input, labels)
|
|
|
|
if index is None:
|
|
mask = (labels > 0)
|
|
masked_positions = None
|
|
if find_positions:
|
|
masked_positions = positions[mask]
|
|
return single_group(input[mask], masked_positions)
|
|
|
|
if numpy.isscalar(index):
|
|
mask = (labels == index)
|
|
masked_positions = None
|
|
if find_positions:
|
|
masked_positions = positions[mask]
|
|
return single_group(input[mask], masked_positions)
|
|
|
|
# remap labels to unique integers if necessary, or if the largest
|
|
# label is larger than the number of values.
|
|
if (not _safely_castable_to_int(labels.dtype) or
|
|
labels.min() < 0 or labels.max() > labels.size):
|
|
# remap labels, and indexes
|
|
unique_labels, labels = numpy.unique(labels, return_inverse=True)
|
|
idxs = numpy.searchsorted(unique_labels, index)
|
|
|
|
# make all of idxs valid
|
|
idxs[idxs >= unique_labels.size] = 0
|
|
found = (unique_labels[idxs] == index)
|
|
else:
|
|
# labels are an integer type, and there aren't too many
|
|
idxs = numpy.asanyarray(index, numpy.int_).copy()
|
|
found = (idxs >= 0) & (idxs <= labels.max())
|
|
|
|
idxs[~ found] = labels.max() + 1
|
|
|
|
if find_median:
|
|
order = numpy.lexsort((input.ravel(), labels.ravel()))
|
|
else:
|
|
order = input.ravel().argsort()
|
|
input = input.ravel()[order]
|
|
labels = labels.ravel()[order]
|
|
if find_positions:
|
|
positions = positions.ravel()[order]
|
|
|
|
result = []
|
|
if find_min:
|
|
mins = numpy.zeros(labels.max() + 2, input.dtype)
|
|
mins[labels[::-1]] = input[::-1]
|
|
result += [mins[idxs]]
|
|
if find_min_positions:
|
|
minpos = numpy.zeros(labels.max() + 2, int)
|
|
minpos[labels[::-1]] = positions[::-1]
|
|
result += [minpos[idxs]]
|
|
if find_max:
|
|
maxs = numpy.zeros(labels.max() + 2, input.dtype)
|
|
maxs[labels] = input
|
|
result += [maxs[idxs]]
|
|
if find_max_positions:
|
|
maxpos = numpy.zeros(labels.max() + 2, int)
|
|
maxpos[labels] = positions
|
|
result += [maxpos[idxs]]
|
|
if find_median:
|
|
locs = numpy.arange(len(labels))
|
|
lo = numpy.zeros(labels.max() + 2, numpy.int_)
|
|
lo[labels[::-1]] = locs[::-1]
|
|
hi = numpy.zeros(labels.max() + 2, numpy.int_)
|
|
hi[labels] = locs
|
|
lo = lo[idxs]
|
|
hi = hi[idxs]
|
|
# lo is an index to the lowest value in input for each label,
|
|
# hi is an index to the largest value.
|
|
# move them to be either the same ((hi - lo) % 2 == 0) or next
|
|
# to each other ((hi - lo) % 2 == 1), then average.
|
|
step = (hi - lo) // 2
|
|
lo += step
|
|
hi -= step
|
|
if (np.issubdtype(input.dtype, np.integer)
|
|
or np.issubdtype(input.dtype, np.bool_)):
|
|
# avoid integer overflow or boolean addition (gh-12836)
|
|
result += [(input[lo].astype('d') + input[hi].astype('d')) / 2.0]
|
|
else:
|
|
result += [(input[lo] + input[hi]) / 2.0]
|
|
|
|
return result
|
|
|
|
|
|
def minimum(input, labels=None, index=None):
|
|
"""
|
|
Calculate the minimum of the values of an array over labeled regions.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array_like of values. For each region specified by `labels`, the
|
|
minimal values of `input` over the region is computed.
|
|
labels : array_like, optional
|
|
An array_like of integers marking different regions over which the
|
|
minimum value of `input` is to be computed. `labels` must have the
|
|
same shape as `input`. If `labels` is not specified, the minimum
|
|
over the whole array is returned.
|
|
index : array_like, optional
|
|
A list of region labels that are taken into account for computing the
|
|
minima. If index is None, the minimum over all elements where `labels`
|
|
is non-zero is returned.
|
|
|
|
Returns
|
|
-------
|
|
minimum : float or list of floats
|
|
List of minima of `input` over the regions determined by `labels` and
|
|
whose index is in `index`. If `index` or `labels` are not specified, a
|
|
float is returned: the minimal value of `input` if `labels` is None,
|
|
and the minimal value of elements where `labels` is greater than zero
|
|
if `index` is None.
|
|
|
|
See also
|
|
--------
|
|
label, maximum, median, minimum_position, extrema, sum, mean, variance,
|
|
standard_deviation
|
|
|
|
Notes
|
|
-----
|
|
The function returns a Python list and not a NumPy array, use
|
|
`np.array` to convert the list to an array.
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy import ndimage
|
|
>>> a = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> labels, labels_nb = ndimage.label(a)
|
|
>>> labels
|
|
array([[1, 1, 0, 0],
|
|
[1, 1, 0, 2],
|
|
[0, 0, 0, 2],
|
|
[3, 3, 0, 0]])
|
|
>>> ndimage.minimum(a, labels=labels, index=np.arange(1, labels_nb + 1))
|
|
[1.0, 4.0, 3.0]
|
|
>>> ndimage.minimum(a)
|
|
0.0
|
|
>>> ndimage.minimum(a, labels=labels)
|
|
1.0
|
|
|
|
"""
|
|
return _select(input, labels, index, find_min=True)[0]
|
|
|
|
|
|
def maximum(input, labels=None, index=None):
|
|
"""
|
|
Calculate the maximum of the values of an array over labeled regions.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array_like of values. For each region specified by `labels`, the
|
|
maximal values of `input` over the region is computed.
|
|
labels : array_like, optional
|
|
An array of integers marking different regions over which the
|
|
maximum value of `input` is to be computed. `labels` must have the
|
|
same shape as `input`. If `labels` is not specified, the maximum
|
|
over the whole array is returned.
|
|
index : array_like, optional
|
|
A list of region labels that are taken into account for computing the
|
|
maxima. If index is None, the maximum over all elements where `labels`
|
|
is non-zero is returned.
|
|
|
|
Returns
|
|
-------
|
|
output : float or list of floats
|
|
List of maxima of `input` over the regions determined by `labels` and
|
|
whose index is in `index`. If `index` or `labels` are not specified, a
|
|
float is returned: the maximal value of `input` if `labels` is None,
|
|
and the maximal value of elements where `labels` is greater than zero
|
|
if `index` is None.
|
|
|
|
See also
|
|
--------
|
|
label, minimum, median, maximum_position, extrema, sum, mean, variance,
|
|
standard_deviation
|
|
|
|
Notes
|
|
-----
|
|
The function returns a Python list and not a NumPy array, use
|
|
`np.array` to convert the list to an array.
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.arange(16).reshape((4,4))
|
|
>>> a
|
|
array([[ 0, 1, 2, 3],
|
|
[ 4, 5, 6, 7],
|
|
[ 8, 9, 10, 11],
|
|
[12, 13, 14, 15]])
|
|
>>> labels = np.zeros_like(a)
|
|
>>> labels[:2,:2] = 1
|
|
>>> labels[2:, 1:3] = 2
|
|
>>> labels
|
|
array([[1, 1, 0, 0],
|
|
[1, 1, 0, 0],
|
|
[0, 2, 2, 0],
|
|
[0, 2, 2, 0]])
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.maximum(a)
|
|
15.0
|
|
>>> ndimage.maximum(a, labels=labels, index=[1,2])
|
|
[5.0, 14.0]
|
|
>>> ndimage.maximum(a, labels=labels)
|
|
14.0
|
|
|
|
>>> b = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> labels, labels_nb = ndimage.label(b)
|
|
>>> labels
|
|
array([[1, 1, 0, 0],
|
|
[1, 1, 0, 2],
|
|
[0, 0, 0, 2],
|
|
[3, 3, 0, 0]])
|
|
>>> ndimage.maximum(b, labels=labels, index=np.arange(1, labels_nb + 1))
|
|
[5.0, 7.0, 9.0]
|
|
|
|
"""
|
|
return _select(input, labels, index, find_max=True)[0]
|
|
|
|
|
|
def median(input, labels=None, index=None):
|
|
"""
|
|
Calculate the median of the values of an array over labeled regions.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array_like of values. For each region specified by `labels`, the
|
|
median value of `input` over the region is computed.
|
|
labels : array_like, optional
|
|
An array_like of integers marking different regions over which the
|
|
median value of `input` is to be computed. `labels` must have the
|
|
same shape as `input`. If `labels` is not specified, the median
|
|
over the whole array is returned.
|
|
index : array_like, optional
|
|
A list of region labels that are taken into account for computing the
|
|
medians. If index is None, the median over all elements where `labels`
|
|
is non-zero is returned.
|
|
|
|
Returns
|
|
-------
|
|
median : float or list of floats
|
|
List of medians of `input` over the regions determined by `labels` and
|
|
whose index is in `index`. If `index` or `labels` are not specified, a
|
|
float is returned: the median value of `input` if `labels` is None,
|
|
and the median value of elements where `labels` is greater than zero
|
|
if `index` is None.
|
|
|
|
See also
|
|
--------
|
|
label, minimum, maximum, extrema, sum, mean, variance, standard_deviation
|
|
|
|
Notes
|
|
-----
|
|
The function returns a Python list and not a NumPy array, use
|
|
`np.array` to convert the list to an array.
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy import ndimage
|
|
>>> a = np.array([[1, 2, 0, 1],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> labels, labels_nb = ndimage.label(a)
|
|
>>> labels
|
|
array([[1, 1, 0, 2],
|
|
[1, 1, 0, 2],
|
|
[0, 0, 0, 2],
|
|
[3, 3, 0, 0]])
|
|
>>> ndimage.median(a, labels=labels, index=np.arange(1, labels_nb + 1))
|
|
[2.5, 4.0, 6.0]
|
|
>>> ndimage.median(a)
|
|
1.0
|
|
>>> ndimage.median(a, labels=labels)
|
|
3.0
|
|
|
|
"""
|
|
return _select(input, labels, index, find_median=True)[0]
|
|
|
|
|
|
def minimum_position(input, labels=None, index=None):
|
|
"""
|
|
Find the positions of the minimums of the values of an array at labels.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array_like of values.
|
|
labels : array_like, optional
|
|
An array of integers marking different regions over which the
|
|
position of the minimum value of `input` is to be computed.
|
|
`labels` must have the same shape as `input`. If `labels` is not
|
|
specified, the location of the first minimum over the whole
|
|
array is returned.
|
|
|
|
The `labels` argument only works when `index` is specified.
|
|
index : array_like, optional
|
|
A list of region labels that are taken into account for finding the
|
|
location of the minima. If `index` is None, the ``first`` minimum
|
|
over all elements where `labels` is non-zero is returned.
|
|
|
|
The `index` argument only works when `labels` is specified.
|
|
|
|
Returns
|
|
-------
|
|
output : list of tuples of ints
|
|
Tuple of ints or list of tuples of ints that specify the location
|
|
of minima of `input` over the regions determined by `labels` and
|
|
whose index is in `index`.
|
|
|
|
If `index` or `labels` are not specified, a tuple of ints is
|
|
returned specifying the location of the first minimal value of `input`.
|
|
|
|
See also
|
|
--------
|
|
label, minimum, median, maximum_position, extrema, sum, mean, variance,
|
|
standard_deviation
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array([[10, 20, 30],
|
|
... [40, 80, 100],
|
|
... [1, 100, 200]])
|
|
>>> b = np.array([[1, 2, 0, 1],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
|
|
>>> from scipy import ndimage
|
|
|
|
>>> ndimage.minimum_position(a)
|
|
(2, 0)
|
|
>>> ndimage.minimum_position(b)
|
|
(0, 2)
|
|
|
|
Features to process can be specified using `labels` and `index`:
|
|
|
|
>>> label, pos = ndimage.label(a)
|
|
>>> ndimage.minimum_position(a, label, index=np.arange(1, pos+1))
|
|
[(2, 0)]
|
|
|
|
>>> label, pos = ndimage.label(b)
|
|
>>> ndimage.minimum_position(b, label, index=np.arange(1, pos+1))
|
|
[(0, 0), (0, 3), (3, 1)]
|
|
|
|
"""
|
|
dims = numpy.array(numpy.asarray(input).shape)
|
|
# see numpy.unravel_index to understand this line.
|
|
dim_prod = numpy.cumprod([1] + list(dims[:0:-1]))[::-1]
|
|
|
|
result = _select(input, labels, index, find_min_positions=True)[0]
|
|
|
|
if numpy.isscalar(result):
|
|
return tuple((result // dim_prod) % dims)
|
|
|
|
return [tuple(v) for v in (result.reshape(-1, 1) // dim_prod) % dims]
|
|
|
|
|
|
def maximum_position(input, labels=None, index=None):
|
|
"""
|
|
Find the positions of the maximums of the values of an array at labels.
|
|
|
|
For each region specified by `labels`, the position of the maximum
|
|
value of `input` within the region is returned.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Array_like of values.
|
|
labels : array_like, optional
|
|
An array of integers marking different regions over which the
|
|
position of the maximum value of `input` is to be computed.
|
|
`labels` must have the same shape as `input`. If `labels` is not
|
|
specified, the location of the first maximum over the whole
|
|
array is returned.
|
|
|
|
The `labels` argument only works when `index` is specified.
|
|
index : array_like, optional
|
|
A list of region labels that are taken into account for finding the
|
|
location of the maxima. If `index` is None, the first maximum
|
|
over all elements where `labels` is non-zero is returned.
|
|
|
|
The `index` argument only works when `labels` is specified.
|
|
|
|
Returns
|
|
-------
|
|
output : list of tuples of ints
|
|
List of tuples of ints that specify the location of maxima of
|
|
`input` over the regions determined by `labels` and whose index
|
|
is in `index`.
|
|
|
|
If `index` or `labels` are not specified, a tuple of ints is
|
|
returned specifying the location of the ``first`` maximal value
|
|
of `input`.
|
|
|
|
See also
|
|
--------
|
|
label, minimum, median, maximum_position, extrema, sum, mean, variance,
|
|
standard_deviation
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy import ndimage
|
|
>>> a = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> ndimage.maximum_position(a)
|
|
(3, 0)
|
|
|
|
Features to process can be specified using `labels` and `index`:
|
|
|
|
>>> lbl = np.array([[0, 1, 2, 3],
|
|
... [0, 1, 2, 3],
|
|
... [0, 1, 2, 3],
|
|
... [0, 1, 2, 3]])
|
|
>>> ndimage.maximum_position(a, lbl, 1)
|
|
(1, 1)
|
|
|
|
If no index is given, non-zero `labels` are processed:
|
|
|
|
>>> ndimage.maximum_position(a, lbl)
|
|
(2, 3)
|
|
|
|
If there are no maxima, the position of the first element is returned:
|
|
|
|
>>> ndimage.maximum_position(a, lbl, 2)
|
|
(0, 2)
|
|
|
|
"""
|
|
dims = numpy.array(numpy.asarray(input).shape)
|
|
# see numpy.unravel_index to understand this line.
|
|
dim_prod = numpy.cumprod([1] + list(dims[:0:-1]))[::-1]
|
|
|
|
result = _select(input, labels, index, find_max_positions=True)[0]
|
|
|
|
if numpy.isscalar(result):
|
|
return tuple((result // dim_prod) % dims)
|
|
|
|
return [tuple(v) for v in (result.reshape(-1, 1) // dim_prod) % dims]
|
|
|
|
|
|
def extrema(input, labels=None, index=None):
|
|
"""
|
|
Calculate the minimums and maximums of the values of an array
|
|
at labels, along with their positions.
|
|
|
|
Parameters
|
|
----------
|
|
input : ndarray
|
|
N-D image data to process.
|
|
labels : ndarray, optional
|
|
Labels of features in input.
|
|
If not None, must be same shape as `input`.
|
|
index : int or sequence of ints, optional
|
|
Labels to include in output. If None (default), all values where
|
|
non-zero `labels` are used.
|
|
|
|
Returns
|
|
-------
|
|
minimums, maximums : int or ndarray
|
|
Values of minimums and maximums in each feature.
|
|
min_positions, max_positions : tuple or list of tuples
|
|
Each tuple gives the N-D coordinates of the corresponding minimum
|
|
or maximum.
|
|
|
|
See Also
|
|
--------
|
|
maximum, minimum, maximum_position, minimum_position, center_of_mass
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array([[1, 2, 0, 0],
|
|
... [5, 3, 0, 4],
|
|
... [0, 0, 0, 7],
|
|
... [9, 3, 0, 0]])
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.extrema(a)
|
|
(0, 9, (0, 2), (3, 0))
|
|
|
|
Features to process can be specified using `labels` and `index`:
|
|
|
|
>>> lbl, nlbl = ndimage.label(a)
|
|
>>> ndimage.extrema(a, lbl, index=np.arange(1, nlbl+1))
|
|
(array([1, 4, 3]),
|
|
array([5, 7, 9]),
|
|
[(0, 0), (1, 3), (3, 1)],
|
|
[(1, 0), (2, 3), (3, 0)])
|
|
|
|
If no index is given, non-zero `labels` are processed:
|
|
|
|
>>> ndimage.extrema(a, lbl)
|
|
(1, 9, (0, 0), (3, 0))
|
|
|
|
"""
|
|
dims = numpy.array(numpy.asarray(input).shape)
|
|
# see numpy.unravel_index to understand this line.
|
|
dim_prod = numpy.cumprod([1] + list(dims[:0:-1]))[::-1]
|
|
|
|
minimums, min_positions, maximums, max_positions = _select(input, labels,
|
|
index,
|
|
find_min=True,
|
|
find_max=True,
|
|
find_min_positions=True,
|
|
find_max_positions=True)
|
|
|
|
if numpy.isscalar(minimums):
|
|
return (minimums, maximums, tuple((min_positions // dim_prod) % dims),
|
|
tuple((max_positions // dim_prod) % dims))
|
|
|
|
min_positions = [tuple(v) for v in (min_positions.reshape(-1, 1) // dim_prod) % dims]
|
|
max_positions = [tuple(v) for v in (max_positions.reshape(-1, 1) // dim_prod) % dims]
|
|
|
|
return minimums, maximums, min_positions, max_positions
|
|
|
|
|
|
def center_of_mass(input, labels=None, index=None):
|
|
"""
|
|
Calculate the center of mass of the values of an array at labels.
|
|
|
|
Parameters
|
|
----------
|
|
input : ndarray
|
|
Data from which to calculate center-of-mass. The masses can either
|
|
be positive or negative.
|
|
labels : ndarray, optional
|
|
Labels for objects in `input`, as generated by `ndimage.label`.
|
|
Only used with `index`. Dimensions must be the same as `input`.
|
|
index : int or sequence of ints, optional
|
|
Labels for which to calculate centers-of-mass. If not specified,
|
|
all labels greater than zero are used. Only used with `labels`.
|
|
|
|
Returns
|
|
-------
|
|
center_of_mass : tuple, or list of tuples
|
|
Coordinates of centers-of-mass.
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array(([0,0,0,0],
|
|
... [0,1,1,0],
|
|
... [0,1,1,0],
|
|
... [0,1,1,0]))
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.measurements.center_of_mass(a)
|
|
(2.0, 1.5)
|
|
|
|
Calculation of multiple objects in an image
|
|
|
|
>>> b = np.array(([0,1,1,0],
|
|
... [0,1,0,0],
|
|
... [0,0,0,0],
|
|
... [0,0,1,1],
|
|
... [0,0,1,1]))
|
|
>>> lbl = ndimage.label(b)[0]
|
|
>>> ndimage.measurements.center_of_mass(b, lbl, [1,2])
|
|
[(0.33333333333333331, 1.3333333333333333), (3.5, 2.5)]
|
|
|
|
Negative masses are also accepted, which can occur for example when
|
|
bias is removed from measured data due to random noise.
|
|
|
|
>>> c = np.array(([-1,0,0,0],
|
|
... [0,-1,-1,0],
|
|
... [0,1,-1,0],
|
|
... [0,1,1,0]))
|
|
>>> ndimage.measurements.center_of_mass(c)
|
|
(-4.0, 1.0)
|
|
|
|
If there are division by zero issues, the function does not raise an
|
|
error but rather issues a RuntimeWarning before returning inf and/or NaN.
|
|
|
|
>>> d = np.array([-1, 1])
|
|
>>> ndimage.measurements.center_of_mass(d)
|
|
(inf,)
|
|
"""
|
|
normalizer = sum(input, labels, index)
|
|
grids = numpy.ogrid[[slice(0, i) for i in input.shape]]
|
|
|
|
results = [sum(input * grids[dir].astype(float), labels, index) / normalizer
|
|
for dir in range(input.ndim)]
|
|
|
|
if numpy.isscalar(results[0]):
|
|
return tuple(results)
|
|
|
|
return [tuple(v) for v in numpy.array(results).T]
|
|
|
|
|
|
def histogram(input, min, max, bins, labels=None, index=None):
|
|
"""
|
|
Calculate the histogram of the values of an array, optionally at labels.
|
|
|
|
Histogram calculates the frequency of values in an array within bins
|
|
determined by `min`, `max`, and `bins`. The `labels` and `index`
|
|
keywords can limit the scope of the histogram to specified sub-regions
|
|
within the array.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Data for which to calculate histogram.
|
|
min, max : int
|
|
Minimum and maximum values of range of histogram bins.
|
|
bins : int
|
|
Number of bins.
|
|
labels : array_like, optional
|
|
Labels for objects in `input`.
|
|
If not None, must be same shape as `input`.
|
|
index : int or sequence of ints, optional
|
|
Label or labels for which to calculate histogram. If None, all values
|
|
where label is greater than zero are used
|
|
|
|
Returns
|
|
-------
|
|
hist : ndarray
|
|
Histogram counts.
|
|
|
|
Examples
|
|
--------
|
|
>>> a = np.array([[ 0. , 0.2146, 0.5962, 0. ],
|
|
... [ 0. , 0.7778, 0. , 0. ],
|
|
... [ 0. , 0. , 0. , 0. ],
|
|
... [ 0. , 0. , 0.7181, 0.2787],
|
|
... [ 0. , 0. , 0.6573, 0.3094]])
|
|
>>> from scipy import ndimage
|
|
>>> ndimage.measurements.histogram(a, 0, 1, 10)
|
|
array([13, 0, 2, 1, 0, 1, 1, 2, 0, 0])
|
|
|
|
With labels and no indices, non-zero elements are counted:
|
|
|
|
>>> lbl, nlbl = ndimage.label(a)
|
|
>>> ndimage.measurements.histogram(a, 0, 1, 10, lbl)
|
|
array([0, 0, 2, 1, 0, 1, 1, 2, 0, 0])
|
|
|
|
Indices can be used to count only certain objects:
|
|
|
|
>>> ndimage.measurements.histogram(a, 0, 1, 10, lbl, 2)
|
|
array([0, 0, 1, 1, 0, 0, 1, 1, 0, 0])
|
|
|
|
"""
|
|
_bins = numpy.linspace(min, max, bins + 1)
|
|
|
|
def _hist(vals):
|
|
return numpy.histogram(vals, _bins)[0]
|
|
|
|
return labeled_comprehension(input, labels, index, _hist, object, None,
|
|
pass_positions=False)
|
|
|
|
|
|
def watershed_ift(input, markers, structure=None, output=None):
|
|
"""
|
|
Apply watershed from markers using image foresting transform algorithm.
|
|
|
|
Parameters
|
|
----------
|
|
input : array_like
|
|
Input.
|
|
markers : array_like
|
|
Markers are points within each watershed that form the beginning
|
|
of the process. Negative markers are considered background markers
|
|
which are processed after the other markers.
|
|
structure : structure element, optional
|
|
A structuring element defining the connectivity of the object can be
|
|
provided. If None, an element is generated with a squared
|
|
connectivity equal to one.
|
|
output : ndarray, optional
|
|
An output array can optionally be provided. The same shape as input.
|
|
|
|
Returns
|
|
-------
|
|
watershed_ift : ndarray
|
|
Output. Same shape as `input`.
|
|
|
|
References
|
|
----------
|
|
.. [1] A.X. Falcao, J. Stolfi and R. de Alencar Lotufo, "The image
|
|
foresting transform: theory, algorithms, and applications",
|
|
Pattern Analysis and Machine Intelligence, vol. 26, pp. 19-29, 2004.
|
|
|
|
"""
|
|
input = numpy.asarray(input)
|
|
if input.dtype.type not in [numpy.uint8, numpy.uint16]:
|
|
raise TypeError('only 8 and 16 unsigned inputs are supported')
|
|
|
|
if structure is None:
|
|
structure = morphology.generate_binary_structure(input.ndim, 1)
|
|
structure = numpy.asarray(structure, dtype=bool)
|
|
if structure.ndim != input.ndim:
|
|
raise RuntimeError('structure and input must have equal rank')
|
|
for ii in structure.shape:
|
|
if ii != 3:
|
|
raise RuntimeError('structure dimensions must be equal to 3')
|
|
|
|
if not structure.flags.contiguous:
|
|
structure = structure.copy()
|
|
markers = numpy.asarray(markers)
|
|
if input.shape != markers.shape:
|
|
raise RuntimeError('input and markers must have equal shape')
|
|
|
|
integral_types = [numpy.int0,
|
|
numpy.int8,
|
|
numpy.int16,
|
|
numpy.int32,
|
|
numpy.int_,
|
|
numpy.int64,
|
|
numpy.intc,
|
|
numpy.intp]
|
|
|
|
if markers.dtype.type not in integral_types:
|
|
raise RuntimeError('marker should be of integer type')
|
|
|
|
if isinstance(output, numpy.ndarray):
|
|
if output.dtype.type not in integral_types:
|
|
raise RuntimeError('output should be of integer type')
|
|
else:
|
|
output = markers.dtype
|
|
|
|
output = _ni_support._get_output(output, input)
|
|
_nd_image.watershed_ift(input, markers, structure, output)
|
|
return output
|