I'd like to construct a (n,n)
-array from a one dimensional array, where each row is shifted (with wrapping) by one relative to the previous one. The following code does this:
import numpy as np
r = np.array([1, 2, 3, 4, 5])
n = len(r)
MM = np.zeros((n, n), dtype=r.dtype)
for k in range(n):
MM[k, :] = np.roll(r, k)
print(MM)
which results in:
[[1 2 3 4 5]
[5 1 2 3 4]
[4 5 1 2 3]
[3 4 5 1 2]
[2 3 4 5 1]]
Is there a way to do this Numpy faster, i.e., avoiding the for
-loop, for large r
in Numpy?
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