python wrote:
> I played around with a few things and this works but was wondering if
> there was a better way to do this.
> My first thought was list comprehension but could not get a figure out
> the syntax.
>
> tag23gr is a list of lists each with two items.
> g23tag is an empty dictionary when I run the for loop below.
> When is is complete each key is a graphic name who's values are a list
> of tags.
>
> for item in tag23gr:
> ... value, key = tuple(item)
> ... if(g23tag.get(key)):
That should be
if key in g23tag:
Your version means trouble for keys that evaluate to False in a boolean
context, e. g. 0, False, None, "", (),...
> ... g23tag[key].append(value)
> ... else:
> ... g23tag[key] = [value]
from collections import defaultdict
g23tag = defaultdict(list)
for value, key in tag23gr:
g23tag[key].append(value)
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