I want to attach a list to itself and I thought this would work:
x = [1,2]
y = x.extend(x)
print y
I wanted to get back [1,2,1,2]
or just:
x = [1,2]
y = x * 2
print y
x.extend(x) will extend x inplace.
>>> print x
[1, 2, 1, 2]
If you want a new copy of the list try:
x = [1,2]
y = x + x
print y # prints [1,2,1,2]
The difference is that extend
modifies the list "in place", meaning it will always return None
even though the list is modified.
x.extend(x)
does not return a new copy, it modifies the list itself.
Just print x
instead.
You can also go with x + x
x.extend(x)
modifies x
in-place.
If you want a new, different list, use y = x + x
.