How I can get rid of None values in dictionary?

Question

Something like:

for (a,b) in kwargs.iteritems():
    if not b : del kwargs[a]

This code raise exception because changing of dictionary when

Answer 1

To anybody who may interests, here's another way to get rid of None value. Instead of deleting the key, I change the value of None with a placeholder for the same key.

One use case is applying with Spark RDD.map onto null valued JSON.

def filter_null(data, placeholder="[spark]nonexists"):
    # Replace all `None` in the dict to the value of `placeholder`
    return dict((k, filter_null(v, placeholder) if isinstance(v, dict) else v if v 
is not None else placeholder) for k, v in data.iteritems())

Sample output:

>>> filter_null({'a':None,'b':"nul", "c": {'a':None,'b':"nul"}})
{'a': '[spark]nonexists', 'c': {'a': '[spark]nonexists', 'b': 'nul'}, 'b': 'nul'}

For python3, change the iteritems() to items().