Generating banded matrices using numpy

Question

I\'m using the following piece of code to create a banded matrix from a generator g:

def banded(g, N):
    \"\"\"Creates a `g` generated banded          


        

Answer 1

You could use scipy.sparse.diags:

Input:

diags([1, 2, 3], [0, 1, 2], shape=(3,5)).toarray()

Output:

array([[ 1.,  2.,  3.,  0.,  0.],
      [ 0.,  1.,  2.,  3.,  0.],
      [ 0.,  0.,  1.,  2.,  3.]])

The second list, [0, 1, 2], is an offset list. It tells how offset from the diagonal you want a certain element to be.