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Python

from os.path import join, dirname
import numpy as np
from numpy.testing import assert_array_almost_equal, assert_equal
import pytest
from pytest import raises as assert_raises
from scipy.fftpack.realtransforms import (
dct, idct, dst, idst, dctn, idctn, dstn, idstn)
# Matlab reference data
MDATA = np.load(join(dirname(__file__), 'test.npz'))
X = [MDATA['x%d' % i] for i in range(8)]
Y = [MDATA['y%d' % i] for i in range(8)]
# FFTW reference data: the data are organized as follows:
# * SIZES is an array containing all available sizes
# * for every type (1, 2, 3, 4) and every size, the array dct_type_size
# contains the output of the DCT applied to the input np.linspace(0, size-1,
# size)
FFTWDATA_DOUBLE = np.load(join(dirname(__file__), 'fftw_double_ref.npz'))
FFTWDATA_SINGLE = np.load(join(dirname(__file__), 'fftw_single_ref.npz'))
FFTWDATA_SIZES = FFTWDATA_DOUBLE['sizes']
def fftw_dct_ref(type, size, dt):
x = np.linspace(0, size-1, size).astype(dt)
dt = np.result_type(np.float32, dt)
if dt == np.double:
data = FFTWDATA_DOUBLE
elif dt == np.float32:
data = FFTWDATA_SINGLE
else:
raise ValueError()
y = (data['dct_%d_%d' % (type, size)]).astype(dt)
return x, y, dt
def fftw_dst_ref(type, size, dt):
x = np.linspace(0, size-1, size).astype(dt)
dt = np.result_type(np.float32, dt)
if dt == np.double:
data = FFTWDATA_DOUBLE
elif dt == np.float32:
data = FFTWDATA_SINGLE
else:
raise ValueError()
y = (data['dst_%d_%d' % (type, size)]).astype(dt)
return x, y, dt
def dct_2d_ref(x, **kwargs):
"""Calculate reference values for testing dct2."""
x = np.array(x, copy=True)
for row in range(x.shape[0]):
x[row, :] = dct(x[row, :], **kwargs)
for col in range(x.shape[1]):
x[:, col] = dct(x[:, col], **kwargs)
return x
def idct_2d_ref(x, **kwargs):
"""Calculate reference values for testing idct2."""
x = np.array(x, copy=True)
for row in range(x.shape[0]):
x[row, :] = idct(x[row, :], **kwargs)
for col in range(x.shape[1]):
x[:, col] = idct(x[:, col], **kwargs)
return x
def dst_2d_ref(x, **kwargs):
"""Calculate reference values for testing dst2."""
x = np.array(x, copy=True)
for row in range(x.shape[0]):
x[row, :] = dst(x[row, :], **kwargs)
for col in range(x.shape[1]):
x[:, col] = dst(x[:, col], **kwargs)
return x
def idst_2d_ref(x, **kwargs):
"""Calculate reference values for testing idst2."""
x = np.array(x, copy=True)
for row in range(x.shape[0]):
x[row, :] = idst(x[row, :], **kwargs)
for col in range(x.shape[1]):
x[:, col] = idst(x[:, col], **kwargs)
return x
def naive_dct1(x, norm=None):
"""Calculate textbook definition version of DCT-I."""
x = np.array(x, copy=True)
N = len(x)
M = N-1
y = np.zeros(N)
m0, m = 1, 2
if norm == 'ortho':
m0 = np.sqrt(1.0/M)
m = np.sqrt(2.0/M)
for k in range(N):
for n in range(1, N-1):
y[k] += m*x[n]*np.cos(np.pi*n*k/M)
y[k] += m0 * x[0]
y[k] += m0 * x[N-1] * (1 if k % 2 == 0 else -1)
if norm == 'ortho':
y[0] *= 1/np.sqrt(2)
y[N-1] *= 1/np.sqrt(2)
return y
def naive_dst1(x, norm=None):
"""Calculate textbook definition version of DST-I."""
x = np.array(x, copy=True)
N = len(x)
M = N+1
y = np.zeros(N)
for k in range(N):
for n in range(N):
y[k] += 2*x[n]*np.sin(np.pi*(n+1.0)*(k+1.0)/M)
if norm == 'ortho':
y *= np.sqrt(0.5/M)
return y
def naive_dct4(x, norm=None):
"""Calculate textbook definition version of DCT-IV."""
x = np.array(x, copy=True)
N = len(x)
y = np.zeros(N)
for k in range(N):
for n in range(N):
y[k] += x[n]*np.cos(np.pi*(n+0.5)*(k+0.5)/(N))
if norm == 'ortho':
y *= np.sqrt(2.0/N)
else:
y *= 2
return y
def naive_dst4(x, norm=None):
"""Calculate textbook definition version of DST-IV."""
x = np.array(x, copy=True)
N = len(x)
y = np.zeros(N)
for k in range(N):
for n in range(N):
y[k] += x[n]*np.sin(np.pi*(n+0.5)*(k+0.5)/(N))
if norm == 'ortho':
y *= np.sqrt(2.0/N)
else:
y *= 2
return y
class TestComplex(object):
def test_dct_complex64(self):
y = dct(1j*np.arange(5, dtype=np.complex64))
x = 1j*dct(np.arange(5))
assert_array_almost_equal(x, y)
def test_dct_complex(self):
y = dct(np.arange(5)*1j)
x = 1j*dct(np.arange(5))
assert_array_almost_equal(x, y)
def test_idct_complex(self):
y = idct(np.arange(5)*1j)
x = 1j*idct(np.arange(5))
assert_array_almost_equal(x, y)
def test_dst_complex64(self):
y = dst(np.arange(5, dtype=np.complex64)*1j)
x = 1j*dst(np.arange(5))
assert_array_almost_equal(x, y)
def test_dst_complex(self):
y = dst(np.arange(5)*1j)
x = 1j*dst(np.arange(5))
assert_array_almost_equal(x, y)
def test_idst_complex(self):
y = idst(np.arange(5)*1j)
x = 1j*idst(np.arange(5))
assert_array_almost_equal(x, y)
class _TestDCTBase(object):
def setup_method(self):
self.rdt = None
self.dec = 14
self.type = None
def test_definition(self):
for i in FFTWDATA_SIZES:
x, yr, dt = fftw_dct_ref(self.type, i, self.rdt)
y = dct(x, type=self.type)
assert_equal(y.dtype, dt)
# XXX: we divide by np.max(y) because the tests fail otherwise. We
# should really use something like assert_array_approx_equal. The
# difference is due to fftw using a better algorithm w.r.t error
# propagation compared to the ones from fftpack.
assert_array_almost_equal(y / np.max(y), yr / np.max(y), decimal=self.dec,
err_msg="Size %d failed" % i)
def test_axis(self):
nt = 2
for i in [7, 8, 9, 16, 32, 64]:
x = np.random.randn(nt, i)
y = dct(x, type=self.type)
for j in range(nt):
assert_array_almost_equal(y[j], dct(x[j], type=self.type),
decimal=self.dec)
x = x.T
y = dct(x, axis=0, type=self.type)
for j in range(nt):
assert_array_almost_equal(y[:,j], dct(x[:,j], type=self.type),
decimal=self.dec)
class _TestDCTIBase(_TestDCTBase):
def test_definition_ortho(self):
# Test orthornomal mode.
for i in range(len(X)):
x = np.array(X[i], dtype=self.rdt)
dt = np.result_type(np.float32, self.rdt)
y = dct(x, norm='ortho', type=1)
y2 = naive_dct1(x, norm='ortho')
assert_equal(y.dtype, dt)
assert_array_almost_equal(y / np.max(y), y2 / np.max(y), decimal=self.dec)
class _TestDCTIIBase(_TestDCTBase):
def test_definition_matlab(self):
# Test correspondence with MATLAB (orthornomal mode).
for i in range(len(X)):
dt = np.result_type(np.float32, self.rdt)
x = np.array(X[i], dtype=dt)
yr = Y[i]
y = dct(x, norm="ortho", type=2)
assert_equal(y.dtype, dt)
assert_array_almost_equal(y, yr, decimal=self.dec)
class _TestDCTIIIBase(_TestDCTBase):
def test_definition_ortho(self):
# Test orthornomal mode.
for i in range(len(X)):
x = np.array(X[i], dtype=self.rdt)
dt = np.result_type(np.float32, self.rdt)
y = dct(x, norm='ortho', type=2)
xi = dct(y, norm="ortho", type=3)
assert_equal(xi.dtype, dt)
assert_array_almost_equal(xi, x, decimal=self.dec)
class _TestDCTIVBase(_TestDCTBase):
def test_definition_ortho(self):
# Test orthornomal mode.
for i in range(len(X)):
x = np.array(X[i], dtype=self.rdt)
dt = np.result_type(np.float32, self.rdt)
y = dct(x, norm='ortho', type=4)
y2 = naive_dct4(x, norm='ortho')
assert_equal(y.dtype, dt)
assert_array_almost_equal(y / np.max(y), y2 / np.max(y), decimal=self.dec)
class TestDCTIDouble(_TestDCTIBase):
def setup_method(self):
self.rdt = np.double
self.dec = 10
self.type = 1
class TestDCTIFloat(_TestDCTIBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 4
self.type = 1
class TestDCTIInt(_TestDCTIBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 1
class TestDCTIIDouble(_TestDCTIIBase):
def setup_method(self):
self.rdt = np.double
self.dec = 10
self.type = 2
class TestDCTIIFloat(_TestDCTIIBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 2
class TestDCTIIInt(_TestDCTIIBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 2
class TestDCTIIIDouble(_TestDCTIIIBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 3
class TestDCTIIIFloat(_TestDCTIIIBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 3
class TestDCTIIIInt(_TestDCTIIIBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 3
class TestDCTIVDouble(_TestDCTIVBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 3
class TestDCTIVFloat(_TestDCTIVBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 3
class TestDCTIVInt(_TestDCTIVBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 3
class _TestIDCTBase(object):
def setup_method(self):
self.rdt = None
self.dec = 14
self.type = None
def test_definition(self):
for i in FFTWDATA_SIZES:
xr, yr, dt = fftw_dct_ref(self.type, i, self.rdt)
x = idct(yr, type=self.type)
if self.type == 1:
x /= 2 * (i-1)
else:
x /= 2 * i
assert_equal(x.dtype, dt)
# XXX: we divide by np.max(y) because the tests fail otherwise. We
# should really use something like assert_array_approx_equal. The
# difference is due to fftw using a better algorithm w.r.t error
# propagation compared to the ones from fftpack.
assert_array_almost_equal(x / np.max(x), xr / np.max(x), decimal=self.dec,
err_msg="Size %d failed" % i)
class TestIDCTIDouble(_TestIDCTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 10
self.type = 1
class TestIDCTIFloat(_TestIDCTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 4
self.type = 1
class TestIDCTIInt(_TestIDCTBase):
def setup_method(self):
self.rdt = int
self.dec = 4
self.type = 1
class TestIDCTIIDouble(_TestIDCTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 10
self.type = 2
class TestIDCTIIFloat(_TestIDCTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 2
class TestIDCTIIInt(_TestIDCTBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 2
class TestIDCTIIIDouble(_TestIDCTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 3
class TestIDCTIIIFloat(_TestIDCTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 3
class TestIDCTIIIInt(_TestIDCTBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 3
class TestIDCTIVDouble(_TestIDCTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 4
class TestIDCTIVFloat(_TestIDCTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 5
self.type = 4
class TestIDCTIVInt(_TestIDCTBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 4
class _TestDSTBase(object):
def setup_method(self):
self.rdt = None # dtype
self.dec = None # number of decimals to match
self.type = None # dst type
def test_definition(self):
for i in FFTWDATA_SIZES:
xr, yr, dt = fftw_dst_ref(self.type, i, self.rdt)
y = dst(xr, type=self.type)
assert_equal(y.dtype, dt)
# XXX: we divide by np.max(y) because the tests fail otherwise. We
# should really use something like assert_array_approx_equal. The
# difference is due to fftw using a better algorithm w.r.t error
# propagation compared to the ones from fftpack.
assert_array_almost_equal(y / np.max(y), yr / np.max(y), decimal=self.dec,
err_msg="Size %d failed" % i)
class _TestDSTIBase(_TestDSTBase):
def test_definition_ortho(self):
# Test orthornomal mode.
for i in range(len(X)):
x = np.array(X[i], dtype=self.rdt)
dt = np.result_type(np.float32, self.rdt)
y = dst(x, norm='ortho', type=1)
y2 = naive_dst1(x, norm='ortho')
assert_equal(y.dtype, dt)
assert_array_almost_equal(y / np.max(y), y2 / np.max(y), decimal=self.dec)
class _TestDSTIVBase(_TestDSTBase):
def test_definition_ortho(self):
# Test orthornomal mode.
for i in range(len(X)):
x = np.array(X[i], dtype=self.rdt)
dt = np.result_type(np.float32, self.rdt)
y = dst(x, norm='ortho', type=4)
y2 = naive_dst4(x, norm='ortho')
assert_equal(y.dtype, dt)
assert_array_almost_equal(y, y2, decimal=self.dec)
class TestDSTIDouble(_TestDSTIBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 1
class TestDSTIFloat(_TestDSTIBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 4
self.type = 1
class TestDSTIInt(_TestDSTIBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 1
class TestDSTIIDouble(_TestDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 2
class TestDSTIIFloat(_TestDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 6
self.type = 2
class TestDSTIIInt(_TestDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 6
self.type = 2
class TestDSTIIIDouble(_TestDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 3
class TestDSTIIIFloat(_TestDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 7
self.type = 3
class TestDSTIIIInt(_TestDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 7
self.type = 3
class TestDSTIVDouble(_TestDSTIVBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 4
class TestDSTIVFloat(_TestDSTIVBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 4
self.type = 4
class TestDSTIVInt(_TestDSTIVBase):
def setup_method(self):
self.rdt = int
self.dec = 5
self.type = 4
class _TestIDSTBase(object):
def setup_method(self):
self.rdt = None
self.dec = None
self.type = None
def test_definition(self):
for i in FFTWDATA_SIZES:
xr, yr, dt = fftw_dst_ref(self.type, i, self.rdt)
x = idst(yr, type=self.type)
if self.type == 1:
x /= 2 * (i+1)
else:
x /= 2 * i
assert_equal(x.dtype, dt)
# XXX: we divide by np.max(x) because the tests fail otherwise. We
# should really use something like assert_array_approx_equal. The
# difference is due to fftw using a better algorithm w.r.t error
# propagation compared to the ones from fftpack.
assert_array_almost_equal(x / np.max(x), xr / np.max(x), decimal=self.dec,
err_msg="Size %d failed" % i)
class TestIDSTIDouble(_TestIDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 1
class TestIDSTIFloat(_TestIDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 4
self.type = 1
class TestIDSTIInt(_TestIDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 4
self.type = 1
class TestIDSTIIDouble(_TestIDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 2
class TestIDSTIIFloat(_TestIDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 6
self.type = 2
class TestIDSTIIInt(_TestIDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 6
self.type = 2
class TestIDSTIIIDouble(_TestIDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 14
self.type = 3
class TestIDSTIIIFloat(_TestIDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 6
self.type = 3
class TestIDSTIIIInt(_TestIDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 6
self.type = 3
class TestIDSTIVDouble(_TestIDSTBase):
def setup_method(self):
self.rdt = np.double
self.dec = 12
self.type = 4
class TestIDSTIVFloat(_TestIDSTBase):
def setup_method(self):
self.rdt = np.float32
self.dec = 6
self.type = 4
class TestIDSTIVnt(_TestIDSTBase):
def setup_method(self):
self.rdt = int
self.dec = 6
self.type = 4
class TestOverwrite(object):
"""Check input overwrite behavior."""
real_dtypes = [np.float32, np.float64]
def _check(self, x, routine, type, fftsize, axis, norm, overwrite_x, **kw):
x2 = x.copy()
routine(x2, type, fftsize, axis, norm, overwrite_x=overwrite_x)
sig = "%s(%s%r, %r, axis=%r, overwrite_x=%r)" % (
routine.__name__, x.dtype, x.shape, fftsize, axis, overwrite_x)
if not overwrite_x:
assert_equal(x2, x, err_msg="spurious overwrite in %s" % sig)
def _check_1d(self, routine, dtype, shape, axis):
np.random.seed(1234)
if np.issubdtype(dtype, np.complexfloating):
data = np.random.randn(*shape) + 1j*np.random.randn(*shape)
else:
data = np.random.randn(*shape)
data = data.astype(dtype)
for type in [1, 2, 3, 4]:
for overwrite_x in [True, False]:
for norm in [None, 'ortho']:
self._check(data, routine, type, None, axis, norm,
overwrite_x)
def test_dct(self):
for dtype in self.real_dtypes:
self._check_1d(dct, dtype, (16,), -1)
self._check_1d(dct, dtype, (16, 2), 0)
self._check_1d(dct, dtype, (2, 16), 1)
def test_idct(self):
for dtype in self.real_dtypes:
self._check_1d(idct, dtype, (16,), -1)
self._check_1d(idct, dtype, (16, 2), 0)
self._check_1d(idct, dtype, (2, 16), 1)
def test_dst(self):
for dtype in self.real_dtypes:
self._check_1d(dst, dtype, (16,), -1)
self._check_1d(dst, dtype, (16, 2), 0)
self._check_1d(dst, dtype, (2, 16), 1)
def test_idst(self):
for dtype in self.real_dtypes:
self._check_1d(idst, dtype, (16,), -1)
self._check_1d(idst, dtype, (16, 2), 0)
self._check_1d(idst, dtype, (2, 16), 1)
class Test_DCTN_IDCTN(object):
dec = 14
dct_type = [1, 2, 3, 4]
norms = [None, 'ortho']
rstate = np.random.RandomState(1234)
shape = (32, 16)
data = rstate.randn(*shape)
@pytest.mark.parametrize('fforward,finverse', [(dctn, idctn),
(dstn, idstn)])
@pytest.mark.parametrize('axes', [None,
1, (1,), [1],
0, (0,), [0],
(0, 1), [0, 1],
(-2, -1), [-2, -1]])
@pytest.mark.parametrize('dct_type', dct_type)
@pytest.mark.parametrize('norm', ['ortho'])
def test_axes_round_trip(self, fforward, finverse, axes, dct_type, norm):
tmp = fforward(self.data, type=dct_type, axes=axes, norm=norm)
tmp = finverse(tmp, type=dct_type, axes=axes, norm=norm)
assert_array_almost_equal(self.data, tmp, decimal=12)
@pytest.mark.parametrize('fforward,fforward_ref', [(dctn, dct_2d_ref),
(dstn, dst_2d_ref)])
@pytest.mark.parametrize('dct_type', dct_type)
@pytest.mark.parametrize('norm', norms)
def test_dctn_vs_2d_reference(self, fforward, fforward_ref,
dct_type, norm):
y1 = fforward(self.data, type=dct_type, axes=None, norm=norm)
y2 = fforward_ref(self.data, type=dct_type, norm=norm)
assert_array_almost_equal(y1, y2, decimal=11)
@pytest.mark.parametrize('finverse,finverse_ref', [(idctn, idct_2d_ref),
(idstn, idst_2d_ref)])
@pytest.mark.parametrize('dct_type', dct_type)
@pytest.mark.parametrize('norm', [None, 'ortho'])
def test_idctn_vs_2d_reference(self, finverse, finverse_ref,
dct_type, norm):
fdata = dctn(self.data, type=dct_type, norm=norm)
y1 = finverse(fdata, type=dct_type, norm=norm)
y2 = finverse_ref(fdata, type=dct_type, norm=norm)
assert_array_almost_equal(y1, y2, decimal=11)
@pytest.mark.parametrize('fforward,finverse', [(dctn, idctn),
(dstn, idstn)])
def test_axes_and_shape(self, fforward, finverse):
with assert_raises(ValueError,
match="when given, axes and shape arguments"
" have to be of the same length"):
fforward(self.data, shape=self.data.shape[0], axes=(0, 1))
with assert_raises(ValueError,
match="when given, axes and shape arguments"
" have to be of the same length"):
fforward(self.data, shape=self.data.shape[0], axes=None)
with assert_raises(ValueError,
match="when given, axes and shape arguments"
" have to be of the same length"):
fforward(self.data, shape=self.data.shape, axes=0)
@pytest.mark.parametrize('fforward', [dctn, dstn])
def test_shape(self, fforward):
tmp = fforward(self.data, shape=(128, 128), axes=None)
assert_equal(tmp.shape, (128, 128))
@pytest.mark.parametrize('fforward,finverse', [(dctn, idctn),
(dstn, idstn)])
@pytest.mark.parametrize('axes', [1, (1,), [1],
0, (0,), [0]])
def test_shape_is_none_with_axes(self, fforward, finverse, axes):
tmp = fforward(self.data, shape=None, axes=axes, norm='ortho')
tmp = finverse(tmp, shape=None, axes=axes, norm='ortho')
assert_array_almost_equal(self.data, tmp, decimal=self.dec)