How do I create a dictionary with keys from a list and values defaulting to say zero

Question

I have a    1 2 3 4  and I want d    1 0  2 0  3 0  4 0   d   dict zip q  0 for x in range 0 len q        works but is ugly  What s a cleaner way

User · Answer

d   dict   x 0  for x in a       edit  Tim s solution is better because it uses generators see the comment to his answer

User · Answer

dict  el 0  for el in a  will work well    Python 2 7 and above also support dict comprehensions  That syntax is  el 0 for el in a

User · Answer

In python version    2 7 and in python 3   d    el 0 for el in a

User · Answer

In addition to Tim s answer  which is very appropriate to your specific example  it s worth mentioning collections defaultdict  which lets you do stuff like this    gt  gt  gt  d   defaultdict int   gt  gt  gt  d 0     1  gt  gt  gt  d  0  1   gt  gt  gt  d 4     1  gt  gt  gt  d  0  1  4  1    For mapping  1  2  3  4  as in your example  it s a fish out of water   But depending on the reason you asked the question  this may end up being a more appropriate technique

User · Answer

d   dict fromkeys a  0    a is the list  0 is the default value  Pay attention not to set the default value to some mutable object  i e  list or dict   because it will be one object used as value for every key in the dictionary  check here for a solution for this case   Numbers strings are safe

[python] How do I create a dictionary with keys from a list and values defaulting to (say) zero?

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