Question

Python:

Could you please say step by step how the output is coming? I understand about importing and getting random number but how the inner loop is working?

Code:

import random

li1 = [[random.randrange(5) for i in range(3)] for j in range(4)]
print("First output : {}".format(li1))

ncol = 4
nrow = 5
li2 = [ [random.randrange(2) for i in range(ncol) ] for j in range(nrow) ]
print("Second output : {}".format(li2))

Output:

First output : [[3, 2, 4], [2, 3, 2], [4, 2, 0], [4, 2, 4]]
Second output : [[0, 1, 1, 0], [1, 1, 1, 0], [1, 0, 1, 1], [0, 1, 1, 0], [1, 1, 1, 0]]

Answer 1

li1 = [[random.randrange(5) for i in range(3)] for j in range(4)]
inner loop:
[random.randrange(5) for i in range(3)] //it generates a list of 3 random numbers in range 0-4 // for example : [0,4,2]
now let x = [random.randrange(5) for i in range(3)]
outer loop:
[[random.randrange(5) for i in range(3)] for j in range(4)]
means
[x for j in range(4)] //it generates a list of 4 x's // here x is a list of 3 random numbers in range 0-4
//so,it generates a 2d 4x3 list //4 lists of list , where each list have 3 random numers in range 0-4