I got a big matrix with size (1200,1200) full of zeros and want to make a chunk of that matrix equal to smaller one of size(120,120) something like
big[0:120, 0:120]=small
1 Answers
Why, big[0:120, 0:120]=small is precisely what you need. That's what broadcasting does. Consider a smaller example that plants a 3x3 matrix of 1s into the upper left corner of a bigger matrix:
big = np.arange(25).reshape(5, 5)
small = np.ones((3, 3))
big[:3, :3] = small
#Or, rather: big[:small.shape[0], :small.shape[1]] = small
big
#array([[ 1, 1, 1, 3, 4],
# [ 1, 1, 1, 8, 9],
# [ 1, 1, 1, 13, 14],
# [15, 16, 17, 18, 19],
# [20, 21, 22, 23, 24]])
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