I am creating a csr sparse array (because I have a lot of empty elements/cells) that I need to use forwards and backwards. That is, I need to input two indices and get the element that corresponds to it ( matrix[0][9]=34) but I also need to be able to get the indices upon just knowing the value is 34. The elements in my array will all be unique. I have looked all over for an answer regarding this, but have not found one, or may have not understood it was what I was looking for if I did! I'm quite new to python, so if you could make sure to let me know what the functions you find do and the steps to retrieve the indices for the element, I would very much appreciate it!
Thanks in advance!
Here's a way of finding a specific value that is applicable to both numpy arrays and sparse matrices
In [119]: A=sparse.csr_matrix(np.arange(12).reshape(3,4))
In [120]: A==10
Out[120]:
<3x4 sparse matrix of type '<class 'numpy.bool_'>'
with 1 stored elements in Compressed Sparse Row format>
In [121]: (A==10).nonzero()
Out[121]: (array([2], dtype=int32), array([2], dtype=int32))
In [122]: (A.A==10).nonzero()
Out[122]: (array([2], dtype=int32), array([2], dtype=int32))