[Baypiggies] nested list to dict question

Jimmy Retzlaff jimmy at retzlaff.com
Tue Dec 28 17:47:53 CET 2010


On Tue, Dec 28, 2010 at 7:51 AM, Vikram K <kpguy1975 at gmail.com> wrote:
> I have a nested list which looks something like this:
>
> x = [['104', '4501919'], ['104', '237681091'], ['104', '7669477'],
> ['100528064', '315259111']]
>
> I wish to convert this to a dict type which looks something like this:
>
> y = {'104': ['4501919', '237681091', '7669477'], '100528064': ['315259111']}

This is a great use for defaultdict (I haven't run this, there might
be a dumb error - but I've written it a gillion times):

from collections import defaultdict

y = defaultdict(list)
for k, v in x:
    y[k].append(v)

See http://docs.python.org/library/collections.html#collections.defaultdict
- your example is almost exactly the same as the example in the docs.

Jimmy

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