How do I concatenate two lists in Python?


Question

How do I concatenate two lists in Python?

Example:

listone = [1, 2, 3]
listtwo = [4, 5, 6]

Expected outcome:

>>> joinedlist
[1, 2, 3, 4, 5, 6]
1
2143
3/17/2019 9:15:29 AM

Accepted Answer

You can use the + operator to combine them:

listone = [1,2,3]
listtwo = [4,5,6]

joinedlist = listone + listtwo

Output:

>>> joinedlist
[1,2,3,4,5,6]
3383
6/7/2019 6:45:16 AM

It's also possible to create a generator that simply iterates over the items in both lists. This allows you to chain lists (or any iterable) together for processing without copying the items to a new list:

import itertools
for item in itertools.chain(listone, listtwo):
   # Do something with each list item

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