How to delete items from a dictionary while iterating over it?

Question

Is it legitimate to delete items from a dictionary in Python while iterating over it?

For example:

for k, v in mydict.iteritems():
   if k == val:
           


        

Answer 1

It's cleanest to use list(mydict):

>>> mydict = {'one': 1, 'two': 2, 'three': 3, 'four': 4}
>>> for k in list(mydict):
...     if k == 'three':
...         del mydict[k]
... 
>>> mydict
{'four': 4, 'two': 2, 'one': 1}

This corresponds to a parallel structure for lists:

>>> mylist = ['one', 'two', 'three', 'four']
>>> for k in list(mylist):                            # or mylist[:]
...     if k == 'three':
...         mylist.remove(k)
... 
>>> mylist
['one', 'two', 'four']

Both work in python2 and python3.