CODEWITHSUNDEEP
pythondictionary
Anastasia
Anastasia

Reputation: 874

Removing multiple keys from nested dictionaries

I have a large dictionary and I want to remove certain keys. I defined a set of unwanted keys, let's say it's called kunwanted. The dictionary looks like this:

   mydic= {'user':{'key1':'12','key2':'20','key3':30},
          'status':{'newk':'12','user':{'key1':'12','key2':'20','key3':30}}}

So, I have key 'user' as a key of mydic and as a key of mydic['status']. Let's say that in kunwanted I have 'key1' and 'key2'. Obviously, I can iterate 2 times through mydic to remove the elements:

for elem in kunwanted:
    if elem in mydic['status']['user']:
        del mydic['status']['user'][elem]

for elem in kunwanted:
    if elem in mydic['user']:
        del mydic['user'][elem]

is there a more efficient way to achieve this?

Upvotes: 1

Views: 510

Answers (4)

Madison May
Madison May

Reputation: 2753

Condensing that into a single for loop should speed up execution slightly.

for elem in kunwanted:
    if elem in mydict['status']['user']:
        del mydic['status']['user'][elem]
    if elem in mydic['user']:
        del mydic['user'][elem]

Upvotes: 0

Steinar Lima
Steinar Lima

Reputation: 7821

Another recursive approach.

def recursive_remove(u_keys, d):
    # Remove keys in current dict
    for unwanted_key in u_keys:
        try:
            del d[unwanted_key]
        except (KeyError, TypeError):
            continue
    # Try to iterate over the items in dict, continue if not iterable
    for key, value in d.iteritems():
        try:
            recursive_remove(u_keys, value)
        except AttributeError:
            continue


my_dict= {'user':{'key1':'12','key2':'20','key3':30},
          'status':{'newk':'12','user':{'key1':'12','key2':'20','key3':30}}}

u_keys = ['key1', 'key2']

recursive_remove(u_keys, my_dict)

Upvotes: 0

dstromberg
dstromberg

Reputation: 7167

Here's a recursive approach:

#!/usr/local/cpython-3.3/bin/python

import pprint

def recursive_remover(unwanted_keys, dictionary):
    for key, value in list(dictionary.items()):
        if isinstance(value, dict):
            recursive_remover(unwanted_keys, value)

        if key in unwanted_keys:
            del dictionary[key]

def main():
    mydict={'user': {'key1':'12','key2':'20','key3':30},
           'status':{'newk':'12','user':{'key1':'12','key2':'20','key3':30}}}

    unwanted_keys = { 'key1', 'key2' }

    recursive_remover(unwanted_keys, mydict)

    pprint.pprint(mydict)

main()

Upvotes: 3

michaeltang
michaeltang

Reputation: 2898

I am not sure I am getting it the right way, following might be helpful

for elem in kunwanted:
    if elem in mydic['user']:
        del mydic['user'][elem]
        break #
    if elem in mydic['status']['user']:
        del mydic['status']['user'][elem]

Upvotes: 0

Related Questions