searching a list of dictionaries for an element in a list.

Sion Arrowsmith siona at chiark.greenend.org.uk
Wed Aug 10 15:13:41 CEST 2005


Dan  <dan at cellectivity.com> wrote:
>> [ someone else wrote: ]
>> I want to search list1, and the result should be all dictionaries where
>> primarycolor is in input. I can do this using a double for-loop, but is
>> there a more efficent way?
>
>Of course.    :-)
>
>L = [dict for dict in list1 if dict['primarycolor'] in input]

Note that (1) shadowing builtin dict is a bad idea and (2) that's
still two nested loops -- I think you do theoretically better with

input_set = set(input)
output_list = [ d for d in dict_list if d['primarycolor'] in input_set ]

but I suspect input would have to be a rather large list to favour
this.

-- 
\S -- siona at chiark.greenend.org.uk -- http://www.chaos.org.uk/~sion/
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