30-seconds-of-code/snippets/transpose_matrix.md

title, tags

title	tags
transpose_matrix	matrix,list,zip,intermediate

Python zip() function takes the iterable elements as input and returns the iterator. Since zip funtion returns a zip object, we can cast it as list wit list().

list(zip([1,2,3],['a','b','c'], [True, False, True]))
# Output: [(1, 'a', True), (2, 'b', False), (3, 'c', True)]

Using *list, we can access to each element of the list

[[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]
# Output: [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]
*[[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]
# Output: [1, 2, 3] [4, 5, 6] [7, 8, 9] [10, 11, 12]

Combining these two elements we can transpose a matrix. We can access to each row of the matrix using the operator * to use them as args of zip() function.

def transpose_matrix(l:list):
    return list(zip(*l))

print(transpose_matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]))
# Output: [(1, 4, 7, 10), (2, 5, 8, 11), (3, 6, 9, 12)]