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# scipy.sparse.identity

scipy.sparse.identity(n, dtype='d', format=None)

  Identity matrix in sparse format

  Returns an identity matrix with shape (n,n) using a given sparse format and dtype. This differs from `eye_array` in that it has a square shape with ones only on the main diagonal. It is thus the multiplicative identity. `eye_array` allows rectangular shapes and the diagonal can be offset from the main one.

  Warning

  This function returns a sparse matrix – not a sparse array. You are encouraged to use `eye_array` to take advantage of the sparse array functionality.

  Parameters:
    n int

      Shape of the identity matrix.

    dtype dtype, optional

      Data type of the matrix

    format str, optional

      Sparse format of the result, e.g., format=”csr”, etc.

  Examples

      >>> import scipy as sp
      >>> sp.sparse.identity(3).toarray()
      array([[ 1.,  0.,  0.],
             [ 0.,  1.,  0.],
             [ 0.,  0.,  1.]])
      >>> sp.sparse.identity(3, dtype='int8', format='dia')
      <3x3 sparse matrix of type '<class 'numpy.int8'>'
              with 3 stored elements (1 diagonals) in DIAgonal format>
      >>> sp.sparse.eye_array(3, dtype='int8', format='dia')
      <3x3 sparse array of type '<class 'numpy.int8'>'
              with 3 stored elements (1 diagonals) in DIAgonal format>