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

listA:

chr1    aatt
chr开发者_高级运维8    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!

---

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

---

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)

---

Use set intersection.

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

---

import numpy as np

np.intersect_nu(list1, list2)

---

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