scipy.sparse矩阵的点例程产生错误

Question

我有一个CSR矩阵:

>> print type(tfidf)
<class 'scipy.sparse.csr.csr_matrix'>

我想取这个CSR矩阵的两行的点积:

>> v1 = tfidf.getrow(1)
>> v2 = tfidf.getrow(2)
>> print type(v1)
<class 'scipy.sparse.csr.csr_matrix'>

无论v1和v2也CSR矩阵.所以我使用dot子程序:

>> print v1.dot(v2)

Traceback (most recent call last):
  File "cosine.py", line 10, in <module>
    print v1.dot(v2)
  File "/usr/lib/python2.7/dist-packages/scipy/sparse/base.py", line 211, in dot
    return self * other
  File "/usr/lib/python2.7/dist-packages/scipy/sparse/base.py", line 246, in __mul__
    raise ValueError('dimension mismatch')
ValueError: dimension mismatch

它们是相同矩阵的行,因此它们的尺寸应该匹配:

>> print v1.shape
(1, 4507)
>> print v2.shape
(1, 4507)

为什么dot子程序不起作用？

谢谢.

Answer 1

要执行两个行向量的点积,您必须转置一个.转置的那个取决于你正在寻找的结果.

import scipy as sp

a = sp.matrix([1, 2, 3])
b = sp.matrix([4, 5, 6])

In [13]: a.dot(b.transpose())
Out[13]: matrix([[32]])

与

In [14]: a.transpose().dot(b)
Out[14]: 
matrix([[ 4,  5,  6],
        [ 8, 10, 12],
        [12, 15, 18]])