Question

I have a dictionary, lets call it myDict, in Python that contains a set of similar dictionaries which all have the entry “turned_on : True” or “turned_on : False“. I want to remove all the entries in myDict that are off, e.g. where “turned_on : False“. In Ruby I would do something like this:

myDict.delete_if { |id,dict| not dict[:turned_on] }

How should I do this in Python?

Answer 1

Straight-forward way:

def delete_if_not(predicate_key, some_dict):
    for key, subdict in some_dict.items():
        if not subdict.get(predicate_key, True):
            del some_dict[key]

Testing:

mydict = {
        'test1': {
                'turned_on': True,
                'other_data': 'foo',
            },
        'test2': {
            'turned_on': False,
            'other_data': 'bar',
            },
        }
delete_if_not('turned_on', mydict)
print mydict

The other answers on this page so far create another dict. They don’t delete the keys in your actual dict.