CODEWITHSUNDEEP
pythonpython-3.xlistdictionary
Qwertford
Qwertford

Reputation: 1189

How to find dictionaries in one list but not in another

Say we have 2 lists of dictionaries L1 and L2.

I want to have a list of dictionaries that are in L2 but not in L1. In my case, I have L1 is a subset of L2 so im not sure if that fact can be used to make any optimizations.

Upvotes: 0

Views: 732

Answers (2)

blhsing
blhsing

Reputation: 106946

You can use list comprehension:

L1 = [{1: 2, 2: 3}, {2: 3, 3: 4}]
L2 = [{1: 2, 2: 3}, {4: 5, 5: 6}]
print([d for d in L2 if d not in L1])

This outputs:

[{4: 5, 5: 6}]

Or if you have a large list of dicts, you should convert L1 to a set of tuples for efficient membership lookup:

set1 = set(tuple(d.items()) for d in L1)
print([d for d in L2 if tuple(d.items()) not in set1])

Upvotes: 4

GraphicalDot
GraphicalDot

Reputation: 2831

solution 

[_dict for _dict in l1 if _dict not in l2]

This will get the dictionaries which are in l1 but not in l2

Upvotes: 2

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