Python: remove dictionary from list, given list of keys to remove

Question

I have an extension question to remove dictionary from list , except that I have a list of dictionary keys I would like to remove from the list.

So, I have something like:

a=[{'id': 1, 'name': 'paul'},{'id': 2, 'name': 'john'},{'id': 3, 'name': 'john2'},{'id': 4, 'name': 'johnasc'}]

now, I have a del_list, like so:

del_id_list=[2,4]

what is the efficient way (assuming list a is LARGE) to delete dictionaries with id from del_list from a ?

Answer 1

one way, recreating the list using a list comprehension (and declaring del_id_list as a set for faster lookup):

a=[{'id': 1, 'name': 'paul'},{'id': 2, 'name': 'john'},{'id': 3, 'name': 'john2'},{'id': 4, 'name': 'johnasc'}]
del_id_list={2,4}

new_a = [d for d in a if d['id'] not in del_id_list]

result:

[{'id': 1, 'name': 'paul'}, {'id': 3, 'name': 'john2'}]

Answer 2

Get acquainted with filter :

result = filter(lambda x: x['id'] not in del_id_list,a)

EDIT:

Regarding the del_id_list itself, if it's long you may want to consider the complexity of the in statement. Maybe a set and even a dict (with arbitrary value) would be better. Check this .

EDIT 2: As @Jean correctly points out, this is a iteration sequence in Py3. Just add list:

result = list(filter(lambda x: x['id'] not in del_id_list,a))

Answer 3

sourceList = [{'id': 1, 'name': 'paul'},{'id': 2, 'name': 'john'},{'id': 3, 'name': 'john2'},{'id': 4, 'name': 'johnasc'}]

del_id_list = [2,4]

for itemDict in sourceList:
  if itemDict['id'] in del_id_list:
    sourceList.remove(itemDict)

print(sourceList) 

Result -> [{'name': 'paul', 'id': 1}, {'name': 'john2', 'id': 3}]