[英]Finding the indices of the rows where there are non-zero entries in a sparse csc_matrix
I have a numpy array, X: 我有一个numpy数组,X:
type(X)
>>> <class 'scipy.sparse.csc.csc_matrix'>
I am interested in finding the indices of the rows where there are non-zero entries, in the 0th column. 我感兴趣的是在第0列中找到存在非零条目的行的索引。 I tried:
我试过了:
getcol = X.getcol(0)
print getcol
which gives me: 这给了我:
(0, 0) 1
(2, 0) 1
(5, 0) 10
This is great, but what I want is a vector that has 0, 2, 5
in it. 这是伟大的,但我要的是具有矢量
0, 2, 5
在里面。
How do I get the indices I'm looking for? 我如何获得我正在寻找的指数?
Thanks for the help. 谢谢您的帮助。
With a CSC matrix you can do the following: 使用CSC矩阵,您可以执行以下操作:
>>> import scipy.sparse as sps
>>> a = np.array([[1, 0, 0],
... [0, 1, 0],
... [1, 0, 1],
... [0, 0, 1],
... [0, 1, 0],
... [1, 0, 1]])
>>> aa = sps.csc_matrix(a)
>>> aa.indices[aa.indptr[0]:aa.indptr[1]]
array([0, 2, 5])
>>> aa.indices[aa.indptr[1]:aa.indptr[2]]
array([1, 4])
>>> aa.indices[aa.indptr[2]:aa.indptr[3]]
array([2, 3, 5])
So aa.indices[aa.indptr[col]:aa.indptr[col+1]]
should get you what you are after. 所以
aa.indices[aa.indptr[col]:aa.indptr[col+1]]
应该能让你得到你想要的东西。
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