What's going on here? Repeating rows in random list of lists.
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by Jesse Aldridge
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Published on 2010-06-14T00:29:36Z
Indexed on
2010/06/14
0:32 UTC
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I expected to get a grid of unique random numbers. Instead each row is the same sequence of numbers. What's going on here?
from pprint import pprint
from random import random
nrows, ncols = 5, 5
grid = [[0] * ncols] * nrows
for r in range(nrows):
for c in range(ncols):
grid[r][c] = int(random() * 100)
pprint(grid)
Example output:
[[64, 82, 90, 69, 36],
[64, 82, 90, 69, 36],
[64, 82, 90, 69, 36],
[64, 82, 90, 69, 36],
[64, 82, 90, 69, 36]]
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