Is there a good way to splice two lists together without resorting to a
manual loop? Say I had 2 lists:
l1 = [a,b,c]
l2 = [1,2,3]
And I want a list:
[a,1,b,2,c,3] as the result.
I've been searching around but I can't seem to find a good example.
Thanks,
Dan McLeran 6 4736 da********@yaho o.com <da********@yah oo.com> wrote: Is there a good way to splice two lists together without resorting to a manual loop? Say I had 2 lists:
l1 = [a,b,c] l2 = [1,2,3]
And I want a list:
[a,1,b,2,c,3] as the result.
I've been searching around but I can't seem to find a good example.
One way:
result = 6*[None]
result[0::2] = l1
result[1::2] = l2
Alex da********@yaho o.com wrote: Is there a good way to splice two lists together without resorting to a manual loop? Say I had 2 lists:
l1 = [a,b,c] l2 = [1,2,3]
And I want a list:
[a,1,b,2,c,3] as the result.
Our good friend itertools can help us out here: from itertools import chain, izip x = ['a', 'b', 'c'] y = [1, 2, 3] list(chain(*izi p(x, y)))
['a', 1, 'b', 2, 'c', 3] # You can splice more than two iterables at once too: z = ['x', 'y', 'z'] list(chain(*izi p(x, y, z)))
['a', 1, 'x', 'b', 2, 'y', 'c', 3, 'z'] # Cleaner to define it as a function: def splice(*its):
return list(chain(*izi p(*its))) splice(x, y)
['a', 1, 'b', 2, 'c', 3] splice(x, y, z)
['a', 1, 'x', 'b', 2, 'y', 'c', 3, 'z']
--Ben
In article <11************ *********@u72g2 000cwu.googlegr oups.com>,
"da********@yah oo.com" <da********@yah oo.com> wrote: Is there a good way to splice two lists together without resorting to a manual loop? Say I had 2 lists:
l1 = [a,b,c] l2 = [1,2,3]
And I want a list:
[a,1,b,2,c,3] as the result.
I've been searching around but I can't seem to find a good example.
Here's one possibility:
list(reduce(lam bda s, t: s + t, zip(L1, L2), ()))
-M
--
Michael J. Fromberger | Lecturer, Dept. of Computer Science http://www.dartmouth.edu/~sting/ | Dartmouth College, Hanover, NH, USA
Thanks, this worked great. Can you explain the syntax of the '*' on the
return value of izip? I've only ever seen this syntax with respect to
variable number of args.
Thanks again. da********@yaho o.com wrote: Thanks, this worked great.
Welcome. :-)
Can you explain the syntax of the '*' on the return value of izip? I've only ever seen this syntax with respect to variable number of args.
When used in a function call (as opposed to a function definition), *
is the "unpacking" operator. Basically, it "flattens" an iterable into
arguments. The docs mention it... http://www.python.org/doc/2.4.2/tut/...00000000000000 http://www.python.org/doc/faq/progra...ion-to-another
....but not in great detail. You can apply * to an arbitrary
expression, e.g.: def f3(a, b, c): pass
f3(1, 2, 3) f3(*range(3)) f3(*[1, 2, 3])
--Ben
>When used in a function call (as opposed to a function definition), * is the "unpacking" operator. Basically, it "flattens" an iterable into arguments. The docs mention it...
Cool, looks like I didn't read carefully enough.
Thanks again. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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