CODEWITHSUNDEEP
pythonlistintersection
Geparada
Geparada

Reputation: 3038

How to intersect two horizontal lists using python?

At the code I'm writing I need to intersect two horizontal list like:

listA:

chr1    aatt
chr8    tagg
chr11   aaaa
chr7    gtag

listB

chr8    tagt
chr1    tttt
chr7    gtag
chr11   aaaa
chr9    atat

#This lists are compounded by one str per line, wich it has a "/t" in the middle. 
#Also note that are in different order

How can I get the intersection between this two list?

desired result:

chr7    gtag
chr11   aaaa

I'm also available to generate lists of two string per line, like this:\

listA:

('chr1', 'aatt')
('chr8', 'tagg')
('chr11', 'aaaa')
('chr7', 'gtag')

listB

('chr8', 'tagt')
('chr1', 'tttt')
('chr7', 'gtag')
('chr11','aaaa')
('chr9', 'atat')

The important matter in this case is that the two columns must be treated as one

thanks for your time!

Upvotes: 1

Views: 464

Answers (5)

SDR
SDR

Reputation: 321

import numpy as np

np.intersect_nu(list1, list2)

Upvotes: 1

Ivan Novick
Ivan Novick

Reputation: 775

Perhaps there is a performance optimization by not creating 2 sets from lists, which requires hashing all the items in the list, but creating only 1 set and iterating through the second list. If you know which list is large and which is small that could also help.

def intersect(smallList, largeList):
    values = set(smallList)
    intersection = []

    for v in largeList:
        if v in values:
            intersection.append(v)

    return intersection

Upvotes: 0

sethoscope
sethoscope

Reputation: 21

Use set intersection.

setC = set(listA) & set(listB)
listC = list(setC) # if you really need a list

Upvotes: 2

Henry
Henry

Reputation: 6620

Use Python sets

listA = (
    ('chr1', 'aatt'),
    ('chr8', 'tagg'),
    ('chr11', 'aaaa'),
    ('chr7', 'gtag'),
)

listB = (
    ('chr8', 'tagt'),
    ('chr1', 'tttt'),
    ('chr7', 'gtag'),
    ('chr11','aaaa'),
    ('chr9', 'atat'),
)

combined = set(listA).intersection(set(listB))
for c, d in combined:
    print c, d

You can also use the & like this:

combined = set(listA) & set(listB)

Upvotes: 4

YXD
YXD

Reputation: 32511

Convert to sets and intersect: set(a) & set(b)

Upvotes: 5

Related Questions