# Generating a list based on other lists in Python

I have two lists `A2` and `J`. I am performing an operation such that whenever `J[0][i]=0`, `A3==[0]`. I present the current and expected output.

``````A2 = [[2, 3, 5], [3, 4, 6], [0, 3, 5], [0, 1, 2, 4, 5, 6], [1, 3, 6], [0, 2, 3, 7, 8, 10],
[1, 3, 4, 8, 9, 11], [5, 8, 10], [5, 6, 7, 9, 10, 11], [6, 8, 11], [5, 7, 8], [6, 8, 9]]

J=[[0, 2, 0, 6, 7, 9, 10]]
A3=[]
for i in range(0,len(J[0])):
if (J[0][i]==0):
A3==[0]
else:
A33=A2[J[0][i]]
A3.append(A33)
print("A3 =",A3)
``````

The current output is

``````A3 = [[0, 3, 5], [1, 3, 4, 8, 9, 11], [5, 8, 10], [6, 8, 11], [5, 7, 8]]
``````

The expected output is

``````A3 = [[0], [0, 3, 5], [0], [1, 3, 4, 8, 9, 11], [5, 8, 10], [6, 8, 11], [5, 7, 8]]
``````

### >Solution :

``````A2 = [[2, 3, 5], [3, 4, 6], [0, 3, 5], [0, 1, 2, 4, 5, 6], [1, 3, 6], [0, 2, 3, 7, 8, 10],
[1, 3, 4, 8, 9, 11], [5, 8, 10], [5, 6, 7, 9, 10, 11], [6, 8, 11], [5, 7, 8], [6, 8, 9]]

J=[[0, 2, 0, 6, 7, 9, 10]]
A3=[]
for i in range(0,len(J[0])):
if (J[0][i]==0):
A3.append([0])  # change here
else:
A33=A2[J[0][i]]
A3.append(A33)
print("A3 =",A3)

#output
A3 = [[0], [0, 3, 5], [0], [1, 3, 4, 8, 9, 11], [5, 8, 10], [6, 8, 11], [5, 7, 8]]
``````

Instead of `A3==[0]` please do `A3.append([0])` as `A3==[0]` is comparing `A3` with `0` and it is doing no change to `A3`