dictionary of list from a file

[keirr]

andrea.spitaleri at gmail.com wrote:
<snip perl example code>
> in python I tried:
> b={}
> a=[]
> for line in fl.readlines():
>          info=lines.split()
>          b[info[0]] = a.append(info[1])
>
> and then
> for i in b:
>      print i,b[i]
> i get
> 2 None
> 7 None
>
> data file is:
> 2 1
> 2 2
> 2 3
> 2 4
> 7 7
> 7 8
> 7 9
> 7 10
>
> Any help??
Andrea,
 first the append method returns None, as you have discovered; it makes
an inplace update (to a in your example) but does not return the list
it has updated.   This has surprised a few people in the past :-)
Here is what I've used before for updating lists values in a
dictionary.

d[key] = d.get(key, []) + [value]

where d is a dict(ionary)

Hope this helps.

 Keir.