Qd5PdZ ddlZn #e$rYnwxYwd dZdZdZd d Zdd ZdS)a  Text Segmentation Metrics 1. Windowdiff Pevzner, L., and Hearst, M., A Critique and Improvement of an Evaluation Metric for Text Segmentation, Computational Linguistics 28, 19-36 2. Generalized Hamming Distance Bookstein A., Kulyukin V.A., Raita T. Generalized Hamming Distance Information Retrieval 5, 2002, pp 353-375 Baseline implementation in C++ http://digital.cs.usu.edu/~vkulyukin/vkweb/software/ghd/ghd.html Study describing benefits of Generalized Hamming Distance Versus WindowDiff for evaluating text segmentation tasks Begsten, Y. Quel indice pour mesurer l'efficacite en segmentation de textes ? TALN 2009 3. Pk text segmentation metric Beeferman D., Berger A., Lafferty J. (1999) Statistical Models for Text Segmentation Machine Learning, 34, 177-210 N1Fct|t|krtd|t|krtdd}tt||z dzD]k}t||||z|||||z|z }|r||z }X|t d|z }l|t||z dzz S)aW Compute the windowdiff score for a pair of segmentations. A segmentation is any sequence over a vocabulary of two items (e.g. "0", "1"), where the specified boundary value is used to mark the edge of a segmentation. >>> s1 = "000100000010" >>> s2 = "000010000100" >>> s3 = "100000010000" >>> '%.2f' % windowdiff(s1, s1, 3) '0.00' >>> '%.2f' % windowdiff(s1, s2, 3) '0.30' >>> '%.2f' % windowdiff(s2, s3, 3) '0.80' :param seg1: a segmentation :type seg1: str or list :param seg2: a segmentation :type seg2: str or list :param k: window width :type k: int :param boundary: boundary value :type boundary: str or int or bool :param weighted: use the weighted variant of windowdiff :type weighted: boolean :rtype: float z!Segmentations have unequal lengthzCWindow width k should be smaller or equal than segmentation lengthsr?)len ValueErrorrangeabscountmin)seg1seg2kboundaryweightedwdindiffs 9lib/python3.11/site-packages/nltk/metrics/segmentation.py windowdiffr1s< 4yyCII<===3t99}} Q    B 3t99q=1$ % %  DQUO))(33d1q1u9o6K6KH6U6UUVV  %KBB #a-- BB TQ$ %%ctj||f}|tj|z|dddf<|tj|z|dddf<|S)Nr)npemptyarange)nrowsncolsins_costdel_costmats r _init_matr!bsZ (E5> " "C29U+++C111I29U+++C1I Jrc@t|D]\}}t|D]x\}} |t|| z z|||fz} || kr |||f} n'|| kr||||dzfz} n|||dz|fz} t| | ||dz|dzf<ydS)Nr) enumerater r ) r rowvcolvrrshift_cost_coeffrrowijcolj shift_costtcosts r_ghd_auxr,isT?? 7 74  7 7GAt)Ct ,<,<>> # Same examples as Kulyukin C++ implementation >>> ghd('1100100000', '1100010000', 1.0, 1.0, 0.5) 0.5 >>> ghd('1100100000', '1100000001', 1.0, 1.0, 0.5) 2.0 >>> ghd('011', '110', 1.0, 1.0, 0.5) 1.0 >>> ghd('1', '0', 1.0, 1.0, 0.5) 1.0 >>> ghd('111', '000', 1.0, 1.0, 0.5) 3.0 >>> ghd('000', '111', 1.0, 2.0, 0.5) 6.0 :param ref: the reference segmentation :type ref: str or list :param hyp: the hypothetical segmentation :type hyp: str or list :param ins_cost: insertion cost :type ins_cost: float :param del_cost: deletion cost :type del_cost: float :param shift_cost_coeff: constant used to compute the cost of a shift. ``shift cost = shift_cost_coeff * |i - j|`` where ``i`` and ``j`` are the positions indicating the shift :type shift_cost_coeff: float :param boundary: boundary value :type boundary: str or int or bool :rtype: float c&g|] \}}|k |Sr0.0rvalrs r zghd.."CCCXa3(??q???rc&g|] \}}|k |Sr0r0r1s rr4zghd..r5rrgr)r7)r#rr!r,) refhyprrr&rref_idxhyp_idx nref_bound nhyp_boundr s ` rghdr>ys\DCCC3CCCGCCCC3CCCGWJWJQ:??s aJ!OOH$$ qZ!^^H$$ JNJNHh G GC S'7Hh8HIII v;rc|Bttt|||dzz }d}t t||z dzD]U}||||z|dk}||||z|dk}||kr|dz }V|t||z dzz S)a Compute the Pk metric for a pair of segmentations A segmentation is any sequence over a vocabulary of two items (e.g. "0", "1"), where the specified boundary value is used to mark the edge of a segmentation. >>> '%.2f' % pk('0100'*100, '1'*400, 2) '0.50' >>> '%.2f' % pk('0100'*100, '0'*400, 2) '0.50' >>> '%.2f' % pk('0100'*100, '0100'*100, 2) '0.00' :param ref: the reference segmentation :type ref: str or list :param hyp: the segmentation to evaluate :type hyp: str or list :param k: window size, if None, set to half of the average reference segment length :type boundary: str or int or bool :param boundary: boundary value :type boundary: str or int or bool :rtype: float Nr-rrr)introundrr r )r8r9rrerrrrhs rpkrEs2 y c#hh#))H"5"5";<== > > C 3s88arEr0rrrIs@    D +&+&+&+&b 7 7 7 ====F"&"&"&"&"&"&s