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# -*- coding: utf-8 -*- |
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# Copyright 2014-2018 by Christopher C. Little. |
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# This file is part of Abydos. |
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# |
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# Abydos is free software: you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation, either version 3 of the License, or |
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# (at your option) any later version. |
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# |
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# Abydos is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with Abydos. If not, see <http://www.gnu.org/licenses/>. |
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"""abydos.clustering. |
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The clustering module implements clustering algorithms such as: |
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- mean pair-wise similarity |
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""" |
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from __future__ import division, unicode_literals |
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from six.moves import range |
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from .distance import sim |
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from .stats import hmean |
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def mean_pairwise_similarity(collection, metric=sim, |
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meanfunc=hmean, symmetric=False): |
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"""Calculate the mean pairwise similarity of a collection of strings. |
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Takes the mean of the pairwise similarity between each member of a |
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collection, optionally in both directions (for asymmetric similarity |
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metrics. |
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:param list collection: a collection of terms or a string that can be split |
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:param function metric: a similarity metric function |
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:param function mean: a mean function that takes a list of values and |
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returns a float |
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:param bool symmetric: set to True if all pairwise similarities should be |
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calculated in both directions |
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:returns: the mean pairwise similarity of a collection of strings |
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:rtype: str |
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>>> mean_pairwise_similarity(['Christopher', 'Kristof', 'Christobal']) |
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0.51980198019801982 |
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>>> mean_pairwise_similarity(['Niall', 'Neal', 'Neil']) |
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0.54545454545454541 |
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""" |
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if hasattr(collection, 'split'): |
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collection = collection.split() |
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if not hasattr(collection, '__iter__'): |
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raise ValueError('collection is neither a string nor iterable type') |
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elif len(collection) < 2: |
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raise ValueError('collection has fewer than two members') |
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collection = list(collection) |
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pairwise_values = [] |
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for i in range(len(collection)): |
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for j in range(i+1, len(collection)): |
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pairwise_values.append(metric(collection[i], collection[j])) |
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if symmetric: |
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pairwise_values.append(metric(collection[j], collection[i])) |
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if not callable(meanfunc): |
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raise ValueError('meanfunc must be a function') |
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return meanfunc(pairwise_values) |
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if __name__ == '__main__': |
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import doctest |
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doctest.testmod() |
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