def list_to_dict(li):
dct = {}
for item in li:
if dct.has_key(item):
dct[item] = dct[item] + 1
else:
dct[item] = 1
return dct
li = [1, 1, 1, 2, 3, 3, 4, 4, 4, 4, 4, 5, 6, 7, 7]
print list_to_dict(li)
Now I am looking for more Pythonic way to do this task. Any ideas?
Posts
9 comments:
Try this:
dict([i, li.count(i)] for i in li)
for ver 2.4 onward this should work
>>> l = [1,1,1,1,2,2,2,3,3,4]
>>> from collections import Counter
>>> f = Counter(l)
>>> f
Counter({1: 4, 2: 3, 3: 2, 4: 1})
I dont know if using default dict is something you would like:
from collections import defaultdict
dct=defaultdict(int)
for i in li: dct[i]+=1
but this is certainly an antidiom:
if dct.has_key(item) #no no
if item in dct #YES
Typo there, I meant version 2.7
There is a nice thread on stackoverflow on this
Andreas
Thanks everyone.
dict(zip(li,li))
While the code samples here are very nice, what I think is the most meaningful technique not used here is to use dictionary's get(key,defaultVal) method.
def list_to_dict(li):
dct = {}
for item in li:
dct[item] = dct.get(item,0) + 1
return dct
li = [1, 1, 1, 2, 3, 3, 4, 4, 4, 4, 4, 5, 6, 7, 7]
print list_to_dict(li)
You can use the get method cleaner.
Using dict's .get method:
def list_to_dict(li):
dct = {}
for item in li:
dct[item] = dct.get(item,0) + 1
return dct
li = [1, 1, 1, 2, 3, 3, 4, 4, 4, 4, 4, 5, 6, 7, 7]
print list_to_dict(li)
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