I want to have a matrix like this below, 3 columns, n rows. Each row sums to one.
[[0, 0, 1], [0, 0.1, 0.9], [0.1, 0.1, 0.8], [0.1, 0.2, 0.7] ...]
Is there a library for doing this?
You can use itertools.combinations_with_replacement to pick 2 partitions out of the 11 slots between 0.0 and 1.0:
from itertools import combinations_with_replacement
[[n / 10 for n in (a, b - a, 10 - b)] for a, b in combinations_with_replacement(range(11), 2)]
This returns:
[[0.0, 0.0, 1.0],
[0.0, 0.1, 0.9],
[0.0, 0.2, 0.8],
[0.0, 0.3, 0.7],
[0.0, 0.4, 0.6],
[0.0, 0.5, 0.5],
[0.0, 0.6, 0.4],
[0.0, 0.7, 0.3],
[0.0, 0.8, 0.2],
[0.0, 0.9, 0.1],
[0.0, 1.0, 0.0],
[0.1, 0.0, 0.9],
[0.1, 0.1, 0.8],
[0.1, 0.2, 0.7],
[0.1, 0.3, 0.6],
[0.1, 0.4, 0.5],
[0.1, 0.5, 0.4],
[0.1, 0.6, 0.3],
[0.1, 0.7, 0.2],
[0.1, 0.8, 0.1],
[0.1, 0.9, 0.0],
[0.2, 0.0, 0.8],
[0.2, 0.1, 0.7],
[0.2, 0.2, 0.6],
[0.2, 0.3, 0.5],
[0.2, 0.4, 0.4],
[0.2, 0.5, 0.3],
[0.2, 0.6, 0.2],
[0.2, 0.7, 0.1],
[0.2, 0.8, 0.0],
[0.3, 0.0, 0.7],
[0.3, 0.1, 0.6],
[0.3, 0.2, 0.5],
[0.3, 0.3, 0.4],
[0.3, 0.4, 0.3],
[0.3, 0.5, 0.2],
[0.3, 0.6, 0.1],
[0.3, 0.7, 0.0],
[0.4, 0.0, 0.6],
[0.4, 0.1, 0.5],
[0.4, 0.2, 0.4],
[0.4, 0.3, 0.3],
[0.4, 0.4, 0.2],
[0.4, 0.5, 0.1],
[0.4, 0.6, 0.0],
[0.5, 0.0, 0.5],
[0.5, 0.1, 0.4],
[0.5, 0.2, 0.3],
[0.5, 0.3, 0.2],
[0.5, 0.4, 0.1],
[0.5, 0.5, 0.0],
[0.6, 0.0, 0.4],
[0.6, 0.1, 0.3],
[0.6, 0.2, 0.2],
[0.6, 0.3, 0.1],
[0.6, 0.4, 0.0],
[0.7, 0.0, 0.3],
[0.7, 0.1, 0.2],
[0.7, 0.2, 0.1],
[0.7, 0.3, 0.0],
[0.8, 0.0, 0.2],
[0.8, 0.1, 0.1],
[0.8, 0.2, 0.0],
[0.9, 0.0, 0.1],
[0.9, 0.1, 0.0],
[1.0, 0.0, 0.0]]