Generating a dense matrix from a sparse matrix in numpy python

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 from scipy.sparse import csr_matrix
 A = csr_matrix([[1,0,2],[0,3,0]])
 >>>A
 <2x3 sparse matrix of type '<type 'numpy.int64'>'
    with 3 stored elements in Compressed Sparse Row format>
 >>> A.todense()
   matrix([[1, 0, 2],
           [0, 3, 0]])
 >>> A.toarray()
      array([[1, 0, 2],
            [0, 3, 0]])

this is an example of how to convert a sparse matrix to a dense matrix taken from scipy

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Updated on September 23, 2020

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  • Admin
    Admin over 3 years

    I have a Sqlite database that contains following type of schema:

    termcount(doc_num, term , count)
    

    This table contains terms with their respective counts in the document. like

    (doc1 , term1 ,12)
    (doc1, term 22, 2)
    .
    .
    (docn,term1 , 10)
    

    This matrix can be considered as sparse matrix as each documents contains very few terms that will have a non-zero value.

    How would I create a dense matrix from this sparse matrix using numpy as I have to calculate the similarity among documents using cosine similarity.

    This dense matrix will look like a table that have docid as the first column and all the terms will be listed as the first row.and remaining cells will contain counts.