how to produce a nested list from two lists in python

Question

I am a newbie in python, I have two lists:

l1 = ['a','b','c','d']
l2 = ['new']

i want to get new list like this

l3 = [('a','new'),('b','new'),('c','new'),('d','new')]

What is the best way to combine the two lists?

Answer 1

>>> from itertools import product
>>> l1 = ['a','b','c','d']
>>> l2 = ['new']
>>> list(product(l1,l2))
[('a', 'new'), ('b', 'new'), ('c', 'new'), ('d', 'new')]

Answer 2

If l2 always just has the one element there is no need to overcomplicate things

l3 = [(x, l2[0]) for x in l1]

Answer 3

See the itertools docs.

In particular, use product for a Cartesian product:

from itertools import product:
l1 = ['a','b','c','d']
l2 = ['new']
# Cast to list for l3 to be a list since product returns a generator
l3 = list(product(l1, l2))  

Answer 4

>>> from itertools import repeat
>>> l1 = ['a','b','c','d']
>>> l2 = ['new']
>>> zip(l1,repeat(*l2))
[('a', 'new'), ('b', 'new'), ('c', 'new'), ('d', 'new')]

Answer 5

You can simply take use of list comprehension without any functions:

l3 = [(x, y) for x in l1 for y in l2]