Question

I have 3 lists:

>>> a = ["12", "a"]
>>> b = ["123", "b"]
>>> c = ["4", "c"]

I put them in a new list:

>>> d = [a,b,c]

When I sort them according to first item of each inner lists:

>>> sorted(d, key=itemgetter(0))
[['12', 'a'], ['123', 'b'], ['4', 'c']]

But I want:

[['4', 'c'], ['12', 'a'], ['123', 'b']]

Also, first item may have leading zero:

>>> a = ["012", "a"]
>>> b = ["0123", "b"]
>>> c = ["04", "c"]

Again, I want to see the sorted list this way:

[['04', 'c'], ['012', 'a'], ['0123', 'b']]

How can I do this?

Answer 1

Just use int() in the key getter:

In [5]: sorted(d, key=lambda x:int(x[0]))
Out[5]: [['4', 'c'], ['12', 'a'], ['123', 'b']]

In the second example:

In [10]: sorted(d, key=lambda x:int(x[0]))
Out[10]: [['04', 'c'], ['012', 'a'], ['0123', 'b']]