Matrix understanding in Python

[RavCOder]

Meanwhile I found this to get inside the matrix and scroll through it

list_zombies_human =[[0,1,1,0,1],[0,1,0,1,0],[0,0,0,0,1],[0,1,0,0,0]]

for mat , arr in enumerate(list_zombies_human):
  for row_1, row in enumerate(arr):     
        print(row)
        for e in row:
            if e == 0:
              e = 1
            print(e)

but I have error in the last loop

Error:
TypeError: 'int' object is not iterable