CODEWITHSUNDEEP
pythonlistpython-2.7combinations
Raghav Shaligram
Raghav Shaligram

Reputation: 309

Combining lists in python

I am trying to combine 2 lists and want to form combinations.

a = ['ibm','dell']
b = ['strength','weekness']

I want to form combinations like ['ibm strength','ibm weekness','dell strength','dell weakness'].

I tried to use zip or concatenated the lists. I also used itertools but it doesn't give me desired output. Please help.

a = ['ibm','dell']
b = ['strength','weekness']
c = a + b
itertools.combinations(c,2)
for a in a:
    for b in b:
        print a +b

Upvotes: 1

Views: 148

Answers (2)

Óscar López
Óscar López

Reputation: 235984

You're looking for product(). Try this:

import itertools

a = ['ibm', 'dell']
b = ['strength', 'weakness']

[' '.join(x) for x in itertools.product(a, b)]
=> ['ibm strength', 'ibm weakness', 'dell strength', 'dell weakness']

To loop over the results don't forget that itertools.product() returns an iterator that can be consumed only once. If you need it at a later time, convert it into a list (as I did above, using a list comprehension) and store the result in a variable, for future use. For example:

lst = list(itertools.product(a, b))
for a, b in lst:
    print a, b

Upvotes: 6

Raymond Hettinger
Raymond Hettinger

Reputation: 226171

For a Cartesian product, you want itertools.product() instead of combinations.

A nested for-loop would also work:

for x in a:
    for y in b:
        c = a + b
        print(c)

Upvotes: 0

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