Python List Comprehensions - Transposing

Question

I\'m just starting out with list comprehensions by the reading the matrix transposing tutorial here. I understand the example, but I\'m trying to figure out a way to transpose t

Answer 1

Assuming all sub lists have the same number of elements:

s = len(matrix[0])
lcomp = [[row[i] for row in matrix] for i in range(s)]

For sublists with mismatching lengths:

s = len(max(matrix, key=len))

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On a side note, you could easily transpose your matrix with zip:

matrix_T = zip(*matrix) # wrap with list() for Python 3

Or use itertools.izip_longest for sublists with mismatching lengths.

Answer 2

You can use another comprehension! They're a very powerful tool.

[[row(i) for row in matrix] for i in range(max(len(r) for r in matrix))]