CODEWITHSUNDEEP
pythonpython-3.x
Doggy Face
Doggy Face

Reputation: 409

How to extract certain value from nested list?

So, I have lists like this

list1 = [1,2,3]
list2 = [[1,4],[2,10],[3,11],[5,15],[20,30]]

I want to extract the numbers if the first number of the list2 is in the list1, therefore the output will be like:

list3 = [1,2,3,4,10,11]

Anyone can help me with how to do that?

Upvotes: 0

Views: 72

Answers (1)

user2390182
user2390182

Reputation: 73450

You can do the following using the transpositional zip(*...) pattern, if the order derives from list2:

from itertools import chain

>>> list(chain(*zip(*(p for p in list2 if p[0] in list1))))
[1, 2, 3, 4, 10, 11]

If the order of the elements is based on the order in list1:

>>> d = dict(list2)
>>> list(chain(list1, map(d.get, list1)))
[1, 2, 3, 4, 10, 11]

Instead of using the cryptic chain(*iterable) pattern, you can also use the more explicit chain.from_iterable(iterable).

Upvotes: 3

Related Questions