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Add reshape() recipe to demonstrate a use case for batched() and chained.from_iterable() (gh-113198)

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Raymond Hettinger 2023-12-15 18:03:44 -06:00 committed by GitHub
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1 changed files with 24 additions and 3 deletions
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Doc/library/itertools.rst
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@ -1036,10 +1036,15 @@ The following recipes have a more mathematical flavor:
# sum_of_squares([10, 20, 30]) -> 1400
return math.sumprod(*tee(it))
def transpose(it):
"Swap the rows and columns of the input."
def reshape(matrix, cols):
"Reshape a 2-D matrix to have a given number of columns."
# reshape([(0, 1), (2, 3), (4, 5)], 3) --> (0, 1, 2), (3, 4, 5)
return batched(chain.from_iterable(matrix), cols)
def transpose(matrix):
"Swap the rows and columns of a 2-D matrix."
# transpose([(1, 2, 3), (11, 22, 33)]) --> (1, 11) (2, 22) (3, 33)
return zip(*it, strict=True)
return zip(*matrix, strict=True)
def matmul(m1, m2):
"Multiply two matrices."
@ -1254,6 +1259,22 @@ The following recipes have a more mathematical flavor:
>>> sum_of_squares([10, 20, 30])
1400
>>> list(reshape([(0, 1), (2, 3), (4, 5)], 3))
[(0, 1, 2), (3, 4, 5)]
>>> M = [(0, 1, 2, 3), (4, 5, 6, 7), (8, 9, 10, 11)]
>>> list(reshape(M, 1))
[(0,), (1,), (2,), (3,), (4,), (5,), (6,), (7,), (8,), (9,), (10,), (11,)]
>>> list(reshape(M, 2))
[(0, 1), (2, 3), (4, 5), (6, 7), (8, 9), (10, 11)]
>>> list(reshape(M, 3))
[(0, 1, 2), (3, 4, 5), (6, 7, 8), (9, 10, 11)]
>>> list(reshape(M, 4))
[(0, 1, 2, 3), (4, 5, 6, 7), (8, 9, 10, 11)]
>>> list(reshape(M, 6))
[(0, 1, 2, 3, 4, 5), (6, 7, 8, 9, 10, 11)]
>>> list(reshape(M, 12))
[(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)]
>>> list(transpose([(1, 2, 3), (11, 22, 33)]))
[(1, 11), (2, 22), (3, 33)]