# Python 3.7.4 (default, Aug  9 2019, 18:34:13) [MSC v.1915 64 bit (AMD64)]
import random
 
# 產生初值                                                          i                   j
a = [[[random.choice(range(10)) for _1 in range(3)] for _2 in range(4)] for _3 in range(5)]
 
# 直觀做法, 先將j拆掉做i次並且複製i個
b = [[]] * len(a[0])
for index in range(len(a[0])): b[index].extend([arr[index] for arr in a])
 
# 迂迴作法, 先將a[i][j]轉置, 然後用sum拆掉, 再複製i個
c = [sum([[a[j][i] for j in range(len(a))] for i in range(len(a[0]))], [])] * len(a[0])
 
 

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