A = ['a','b','c']
B = ['d','b','e']
res = [i for i in A if i in B]
The above code does not work when the no of elements in A are 300000 and in B are 200000.
How can I solve it?
I also tried
res = {i for i in A if i in B}
res = list(res)
But still could not get the result.
If preserving order and/or duplicates doesn't matter, then you can use
A = ['a', 'b', 'c']
B = ['d', 'e', 'f']
res = list(set(A) & set(B))
If order and/or duplicates does matter, then you can use
A = ['a', 'b', 'c']
B = ['d', 'e', 'f']
set_b = set(B)
res = [i for i in A if i in set_b]
filter(set(B).__contains_, A)A = ['a','b','c']
B = ['d','b','e']
set(A).intersection(B)
To get a list returned:
list(set(A).intersection(B))
intersection takes any iterable as an argument so you just need to make A a set.
Note, the non-operator versions of union(), intersection(), difference(), and symmetric_difference() will accept any iterable as an argument.
(set(B))?
A too and also affect the order if it matters, OP's first example is not doing that.
set increases the time by 50% on my computer on a test case of the size OP specifiedYou are basically computing the intersection of two sets. Using the set data type for this will make this efficient:
A = {'a','b','c'}
B = {'d','b','e'}
res = A & B
set(A) & set(B)
Bto a set first:B = set(B), then use the list comprehension.A = set(A)andB = set(B), then do the intersectionres = A & B?