Python, get method for dictionaries

Question

I try to use get method of dictionaries to avoid an if-else structure, but the method returns a None object, whereas I want a list. My code :

dic = {}
words = ['foo', 'bar']
for word in words :
    long = len(word)
    dic[long] = dic.get(long, []).append(word)

I want to have (at the end of the loop) :

{3:['foo', 'bar']}

But I have :

AttributeError: 'NoneType' object has no attribute 'append'

Which means that get returned a None object (default value)... where I though it should return a void list if the key doesn't exists, a list filled withs some strings if the key exists. Any ideas ?

You'll probably have an easier time if you just use [`collections.defaultdict`](https://docs.python.org/2.7/library/collections.html#collections.defaultdict). — BrenBarn, Oct 20 '15 at 17:52

score -1 · Answer 1 · edited Oct 20 '15 at 22:43

-1

dic = {}
words = ['foo', 'bar']
for word in words :
    long = len(word)
    if (dic.has_key(long)):
        dic[long].append(word)
    else:
        dic[long] = [word]

edited Oct 20 '15 at 22:43

o-90

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answered Oct 20 '15 at 17:55

pausag

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Python, get method for dictionaries

1 Answers1