23 строки
468 B
Python
23 строки
468 B
Python
"""
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Helper functions for calculating correlation coefficients between lists of
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items.
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Check the function docs, they expect specific preconditions.
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"""
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# Placeholders for the fast functions implemented in C.
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def symmetric_diff_count(xs, ys):
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return len(set(xs).symmetric_difference(ys))
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def similarity(xs, ys):
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return 1. / (1. + symmetric_diff_count(xs, ys))
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try:
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from _recommend import symmetric_diff_count, similarity
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except ImportError:
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pass
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