Jaccard vs cityblock

>>> b  =np.array([[1,0,1,1,1],[1,0,0,1,1]]).T
>>> b
array([[1, 1],
       [0, 0],
       [1, 0],
       [1, 1],
       [1, 1]])
>>> ss.distance.squareform(ss.distance.pdist(b))
array([[ 0.        ,  1.41421356,  1.        ,  0.        ,  0.        ],
       [ 1.41421356,  0.        ,  1.        ,  1.41421356,  1.41421356],
       [ 1.        ,  1.        ,  0.        ,  1.        ,  1.        ],
       [ 0.        ,  1.41421356,  1.        ,  0.        ,  0.        ],
       [ 0.        ,  1.41421356,  1.        ,  0.        ,  0.        ]])
>>> ss.distance.squareform(ss.distance.pdist(b, 'cityblock'))
array([[ 0.,  2.,  1.,  0.,  0.],
       [ 2.,  0.,  1.,  2.,  2.],
       [ 1.,  1.,  0.,  1.,  1.],
       [ 0.,  2.,  1.,  0.,  0.],
       [ 0.,  2.,  1.,  0.,  0.]])
>>> ss.distance.squareform(ss.distance.pdist(b, 'jaccard'))
array([[ 0. ,  1. ,  0.5,  0. ,  0. ],
       [ 1. ,  0. ,  1. ,  1. ,  1. ],
       [ 0.5,  1. ,  0. ,  0.5,  0.5],
       [ 0. ,  1. ,  0.5,  0. ,  0. ],
       [ 0. ,  1. ,  0.5,  0. ,  0. ]])

jaccard는 둘 다 0일때 무시한다. intersection=and, union=or 이기 때문. jaccard=intersection/union