problem with two-dimensional list/array

[peachdot]

hi,

i've created a 2D list(ie: A=[]). i choose some of element from the list(ie: A[0][0],A[1][1],A[2][2]) and do simple add operations.

Then i created another empty 2D list to store the result. but i wanted the result to be stored at a specific index (ie: at B=[0][0],B[1][1],B[2][2]).

but i get an error."Error - list index out of range "

here is my code...can anyone spot my mistake...

A=[]
        for i in range(3):
            A.append([])
A[0]=(1,3,4,5)
A[1]=(2,4,6,5)
A[2]=(3,6,7,4)
 
B=[]
      for j in range(3):
             B.append([])
             for i in range(3):
                 B[i][i]=2+A[i][i]
 
 

[bvdet]

Your indentation is wrong, but I suspect it is a copy/paste problem.

You did not initialize list B properly.

A=[]
for i in range(3):
    A.append([])
A[0]=(1,3,4,5)
A[1]=(2,4,6,5)
A[2]=(3,6,7,4)
 
B=[[None for i in range(4)] for j in range(3)]
 
for i in range(3):
    B[i][i]=2+A[i][i]

>>> B
[[3, None, None, None], [None, 6, None, None], [None, None, 9, None]]
>>> 

[dwblas]

Then i created another empty 2D list to store the result.

You can use an intermediate list for this as well, unless I misunderstand.

A=[]
A.append((1,3,4,5))
A.append((2,4,6,5))
A.append((3,6,7,4))
 
B=[]
for j in range(3):
    temp_list = []     ## starts as empty for each "j" loop
    for k in range(4):
        temp_list.append(2+A[j][k])
 
    B.append(temp_list)