问题描述
给出形状为1.000.000 x 70.000的类型为scipy.sparse.coo_matrix的稀疏矩阵R，我发现了
Given a sparse matrixR of type scipy.sparse.coo_matrix of shape 1.000.000 x 70.000 I figured out that
row_maximum = max(R.getrow(i).data)
将给我第i行的最大值.
will give me the maximum value of the i-th row.
我现在需要的是与值row_maximum对应的索引.
What I need now is the index corresponding to the value row_maximum.
有什么想法可以实现这一目标吗?
Any ideas how to achieve that?
谢谢您的任何建议！
推荐答案
getrow(i)返回1 x n CSR矩阵，该矩阵具有indices属性，该属性给出data属性中相应值的行索引. (我们知道形状是1 x n，因此我们不必处理indptr属性.)因此这将起作用:
getrow(i) returns a 1 x n CSR matrix, which has an indices attribute that gives the row indices of the corresponding values in the data attribute. (We know the shape is 1 x n, so we don't have to deal with the indptr attribute.) So this will work:
row = R.getrow(i)
max_index = row.indices[row.data.argmax()] if row.nnz else 0
我们必须分别处理row.nnz为0的情况，因为如果row.data为空数组，则row.data.argmax()将引发异常.
We have to deal with the case where row.nnz is 0 separately, because row.data.argmax() will raise an exception if row.data is an empty array.
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