challenge256.py

#!/usr/bin/python3
# (c) 2016 lsp
# /r/dailyprogrammer

def deoblique(matrix):
    n = 0
    for row in oblique:
        p = min(n, size-1)
        for i in range(len(row)):
            matrix[n-p+i][p-i] = row[i]
        n += 1

# read in oblique matrix
file_path = input("Enter file name:")
oblique = []
with open(file_path) as f:
    for line in f:
        oblique.append([int(i) for i in line.strip().split()])

# construct new one
size = max([len(s) for s in oblique])
matrix = [[0 for i in range(size)] for j in range(size)]

# run over matrix
matrix = oblique(matrix)

for row in matrix:
    print(row)