ณ๒ 4าวIc@s1dZd„Zd„Zd„Zdd„ZdS(s# Tools for comparing ranked lists. ccsft|ƒ}t|ƒ}xG|iƒD]9\}}y||||fVWq%tj oq%Xq%WdS(sธFinds the difference between the values in ranks1 and ranks2 for keys present in both dicts. If the arguments are not dicts, they are converted from (key, rank) sequences. N(tdictt iteritemstKeyError(tranks1tranks2tktv1((s+/p/zhu/06/nlp/nltk/nltk/metrics/spearman.pyt _rank_dists s   c Csˆd}d}x5t||ƒD]$\}}|||7}|d7}qWy&ddt|ƒ|||dSWntj o dSnXdS(sUReturns the Spearman correlation coefficient for two rankings, which should be dicts or sequences of (key, rank). The coefficient ranges from -1.0 (ranks are opposite) to 1.0 (ranks are identical), and is only calculated for keys in both rankings (for meaningful results, remove keys present in only one list before ranking).iiigN(RtfloattZeroDivisionError(RRtntresRtd((s+/p/zhu/06/nlp/nltk/nltk/metrics/spearman.pytspearman_correlations &cCsd„t|ƒDƒS(sƒGiven a sequence, yields each element with an increasing rank, suitable for use as an argument to L{spearman_correlation}. css%x|]\}}||fVqWdS(N((t.0tiR((s+/p/zhu/06/nlp/nltk/nltk/metrics/spearman.pys 0s(t enumerate(tseq((s+/p/zhu/06/nlp/nltk/nltk/metrics/spearman.pytranks_from_sequence,sgV็žฏา s