+ h^XRt^RItRRltRtRtRRltR RltR# ]dL i;i) 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 Nc\V4\V48wd \R4hV\V48d \R4h^p\\V4V, ^,4Fhp\WWb,P V4WWb,P V4, 4pV'd WW, pKUV\ ^V4, pKj V\V4V, R,, #)a 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 lengths?)len ValueErrorrangeabscountmin)seg1seg2kboundaryweightedwdindiffs&&&&& ;/usr/lib/python3/dist-packages/nltk/metrics/segmentation.py windowdiffr1s< 4yCI<==3t9} Q   B 3t9q=1$ %DQUO))(3dquo6K6KH6UUV  KB #a- B & TQ$ %%c\P!W34pV\P!V4,VR&V\P!V4,VR&V#))rNNN)rr)npemptyarange)nrowsncolsins_costdel_costmats&&&& r _init_matr bsE ((E> "C299U++CI299U++CI Jrcl\V4Fwrg\V4FwrV\Wy, 4,WV3,,p Wy8Xd WV3,p M6Wy8dW@Wh^,3,,p MW0V^,V3,,p \W4W^,V^,3&K K R#)N) enumeraterr ) rrowvcolvrrshift_cost_coeffrrowijcolj shift_costtcosts &&&&&& r_ghd_auxr,isT? GA)C ,<>> # 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 g)r.)r#rr r,float) refhyprrr&r rvalref_idxhyp_idx nref_bound nhyp_boundrs &&&&&& rghdr7ys\"+3CXa3?qqGC!*3CXa3?qqGCWJWJQ:? aJ!O$$ qZ!^$$ JNJNH GC S7hI V DCs CC CCcVf;\\\V4VPV4R,, 44p^p\ \V4V, ^,4FLpWWR,PV4^8pWWR,PV4^8pWg8wgKCV^, pKN V\V4V, R,, #)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 @r)introundrrr)r0r1r r errrrhs&&&& rpkr?s2 y c#h#))H"5";<= > C 3s8arEsC@  +&b 7 =F"&_  s ))