Append to python List

[RAHUL RAJ]

Checkout the following code:

sample2 = [x+y for x in range(1,10) for y in range(1,10) if x!=y]   
output=[]
output=[x for x in sample2 if x not in output]

the output I get is
3 4 5 6 7 8 9 10 3 5 6 7 8 9 10 11 4 5 7 8 9 10 11 12 5 6 7 9 10 11 12 13 6 7 8 9 11 12 13 14 7 8 9 10 11 13 14 15 8 9 10 11 12 13 15 16 9 10 11 12 13 14 15 17 10 11 12 13 14 15 16 17

which contains duplicate values.




But if I do like this:

sample2 = [x+y for x in range(1,10) for y in range(1,10) if x!=y]   
output=[]
for x in sample2:
  if x not in output:
     output.append(x)


the value of 'output' I get like this:
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

I know that both the programs have the same functionality, but why do I have different outputs?

Please help!