On Mar 28, 1:44 pm, <[EMAIL PROTECTED]> wrote:
> Hi everyone.
>
> I'm trying to work with very simple data structures but I'm stuck in the very
> first steps. If someone has the luxury of a few minutes and can give an
> advice how to resolve this, I'll really appreciate it.
>
> 1- I have a list of tuples like this:
> lista= [(162, 141, 3), (162, 141, 3), (162, 141, 3), (168, 141, 2), (168,
> 141, 2), (168, 141, 2), (201, 141, 1), (213, 141, 1), (203, 141, 1), (562,
> 142, 4), (562, 142, 4), (562, 142, 4), (568, 142, 2), (568, 142, 2), (568,
> 142, 2), (501, 142, 1), (513, 142, 1), (503, 142, 1)]
> and I want to end with a dict like this:
> {141: {1: [203, 213, 201], 2: [168, ], 3: [162, ]}, 142: {1: [503, 513, 501],
> 2: [568, ], 4: [562, ]}}
(snipped)
I think you can use, with python 2.5, defaultdict for
this. I only have access to 2.4.4 here, so my facsimile
is:
class defaultd(dict):
def __getitem__(self, k):
if k not in self:
self[k] = defaultd()
return dict.__getitem__(self, k)
lista = [(162, 141, 3), (162, 141, 3), (162, 141, 3), (168, 141, 2),
(168, 141, 2), (168, 141, 2), (201, 141, 1), (213, 141, 1), (203,
141,
1), (562, 142, 4), (562, 142, 4), (562, 142, 4), (568, 142, 2), (568,
142, 2), (568, 142, 2), (501, 142, 1), (513, 142, 1), (503, 142, 1)]
dd = defaultd()
for value, outerkey, innerkey in lista:
li = dd[outerkey].setdefault(innerkey, [])
if value not in li:
li.insert(0, value)
# or, li.append(value) if you want to reverse order
print dd
I happen to like the "autovivification" feature
found in perl and was pleased to see defaultdict in
python 2.5. OTOH, python programmers more experienced
than I might see this and run away screaming.
--
Hope this helps,
Steven
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