about sort a list with integer key

[lotrpy]

hi, if I want sort each line ,by the last part,of a file, below is the
source.
from operator import itemgetter
content = (line.split() for line in file('foo.txt', 'rb'))
for cursor, line in enumerate(sorted(content, key = itemgetter(-1),
reverse = True)):
print cursor, ' '.join(line)
the content of foo.txt is
21 job
3 joke
the result is
0 3 joke
1 21 job

if i want sort each line by the first part,(it's a integer, in fact).
don't know how to do it with itemgetter.
key = int(itemgetter(0)) is wrong, key = lambda x:int(x[0]) works.
but s.b. told me itemgetter execute more quickly .

[Fredrik Lundh]

lotrpy wrote:

key = int(itemgetter(0)) is wrong, key = lambda x:int(x[0]) works.
but s.b. told me itemgetter execute more quickly .

so you're more interested in speed than in correctness? ;-)

operator.itemgetter is a function factory that creates a *function* that
fetches the given item from a sequence. or in other words, typing

func = itemgetter(0)

is pretty much the same thing as typing

def func(seq):
return seq[0]

given this, it should be fairly obvious what int(itemgetter(0)) does: it
attemts to convert the *function* to an integer, which obviously doesn't
work.

I'd stick to the lambda form if I were you. It isn't only easier to
understand for the Python layman, it also does the right thing.

</F>