How I can subset a list of lists?-CodePudding

I have the following two lists:

list_dummy = [['a', 'b', 'c'], ['d', 'b', 'c'], ['a', 'b', 'd'], ['d', 'a', 'c'] ]
must_have = ['a', 'b']

I want to "subset" the first list, meaning that I only want to keep the lists within list_dummy that have the elements a and b

The expected result should be:

list_sub = [['a', 'b', 'c'], ['a', 'b', 'd']]

How I can do this in python and please also consider that the list_dummy might be large so some scalable solution would be appreciated.

CodePudding user response：

You can convert them to sets and then check if their intersection is same as the must_have set.

list_dummy = [['a', 'b', 'c'], ['d', 'b', 'c'], ['a', 'b', 'd'], ['d', 'a', 'c'] ]
must_have = ['a', 'b']
must_have_set = set(must_have)
print([x for x in list_dummy if set(x) & must_have_set == must_have_set])

CodePudding user response：

You can use issubset

list_dummy = [['a', 'b', 'c'], ['d', 'b', 'c'], ['a', 'b', 'd'], ['d', 'a', 'c']]
must_have = ['a', 'b']
list_sub = [i for i in list_dummy if set(must_have).issubset(i)]
print(list_sub)