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pythondictionarydefaultdict

python collections.defaultdict() compile error

The following code, simple and clear enough, produces an error when compiled:

import string
import collections

#create dictionary with alphabets as keys, and empty values
list = ['aema', 'airplane', 'amend']

gen_dict = dict.fromkeys(string.ascii_lowercase, '')

gen_dict = collections.defaultdict(list)

for x in list:
    gen_dict['a'].append(x)

and the error produced is:

Traceback (most recent call last):
  File "indexdict.py", line 14, in <module>
    gen_dict = collections.defaultdict(list)
TypeError: first argument must be callable

any idea? thanks in advance

Solution

  • you overwrite the internal list, being the name of a type, with your list = ['aema', 'airplane', 'amend'] above. Rename your list to e.g. keys or keylist and all will be fine.

    So replace

    list = ['aema', 'airplane', 'amend']

    with

    keys = ['aema', 'airplane', 'amend']

    and 

    for x in list:

    with

    for x in keys: