How to find the mirror of an identity matrix without using numpy?

Question

Here I have an identity matrix that goes from top left to bottom right. I'm trying to flip it so I can get a row of 1's going from top right to bottom left but I don't want to use numpy. But I just cant work out how to do it...

num = int(input("enter your number"))
for i in range(0, num):
    for j in range(0, num):
        if (i == j):
            print(1, sep=" ", end=" ")
        else:
            print(0, sep=" ", end=" ")
    print()

Example:
Input: 4
Output:

1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

Answer 1

There is simple relation between column, row and num

if i + j + 1 == num:

---

Full code:

num = int(input("enter your number"))
for i in range(0, num):
    for j in range(0, num):
        if i + j + 1 == num:
            print(1, sep=" ", end=" ")
        else:
            print(0, sep=" ", end=" ")
    print()

---

EDIT:

Other idea is to revers one range

for j in range(num-1, -1, -1):

---

Full code:

num = int(input("enter your number"))
for i in range(0, num):
    for j in range(num-1, -1, -1):
        if i == j:
            print(1, sep=" ", end=" ")
        else:
            print(0, sep=" ", end=" ")
    print()