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# Natural Language Toolkit: Dispersion Plots
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#
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# Copyright (C) 2001-2020 NLTK Project
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# Author: Steven Bird <stevenbird1@gmail.com>
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# URL: <http://nltk.org/>
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# For license information, see LICENSE.TXT
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"""
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A utility for displaying lexical dispersion.
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"""
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def dispersion_plot(text, words, ignore_case=False, title="Lexical Dispersion Plot"):
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"""
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Generate a lexical dispersion plot.
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:param text: The source text
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:type text: list(str) or enum(str)
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:param words: The target words
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:type words: list of str
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:param ignore_case: flag to set if case should be ignored when searching text
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:type ignore_case: bool
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"""
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try:
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from matplotlib import pylab
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except ImportError:
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raise ValueError(
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"The plot function requires matplotlib to be installed."
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"See http://matplotlib.org/"
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)
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text = list(text)
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words.reverse()
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if ignore_case:
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words_to_comp = list(map(str.lower, words))
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text_to_comp = list(map(str.lower, text))
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else:
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words_to_comp = words
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text_to_comp = text
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points = [
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(x, y)
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for x in range(len(text_to_comp))
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for y in range(len(words_to_comp))
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if text_to_comp[x] == words_to_comp[y]
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]
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if points:
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x, y = list(zip(*points))
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else:
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x = y = ()
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pylab.plot(x, y, "b|", scalex=0.1)
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pylab.yticks(list(range(len(words))), words, color="b")
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pylab.ylim(-1, len(words))
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pylab.title(title)
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pylab.xlabel("Word Offset")
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pylab.show()
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if __name__ == "__main__":
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from nltk.corpus import gutenberg
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words = ["Elinor", "Marianne", "Edward", "Willoughby"]
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dispersion_plot(gutenberg.words("austen-sense.txt"), words)
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