["python","list","dictionary","loops"]
How to avoid "RuntimeError: dictionary changed size during iteration" error?

Suppose I have a dictionary of lists: d = {'a': [1], 'b': [1, 2], 'c': [], 'd':[]} Now I want to remove key-value pairs where the values are empty lists. I tried this code: for i in d: if not d[i]: d.pop(i) but this gives an error: RuntimeError: dictionary changed size during iteration I understand that entries can't be added or removed from a dictionary while iterating through it. How can I work around this limitation in order to solve the problem? See Modifying a Python dict while iterating over it for citations that this can cause problems, and why.
In Python 3.x and 2.x you can use use list to force a copy of the keys to be made: for i in list(d): In Python 2.x calling .keys made a copy of the keys that you could iterate over while modifying the dict: for i in d.keys(): but on Python 3.x, .keys returns a view object instead, so it won't fix your error.