基于两个列表的元素的格式化字符串列表

Question

I am trying to join two lists in such a manner in Python 2.7:

a = ['x','y','z']
b = [1,2,3]

and the end result should be:

c=['x1','y2','z3']

How do I do that?

Answer 1

c = [p + str(q) for p, q in zip(a, b)]

Answer 2

Instead of concatenating the string, it is even better to use string.format function. You can also use it with itertools.starmap with the zip version of the lists as:

>>> from itertools import starmap
>>> a = ['x','y','z']
>>> b = [1,2,3]

>>> list(starmap("{}{}".format, zip(a, b)))
['x1', 'y2', 'z3']

# Note: `starmap` returns an iterator. If you want to iterate this value
# only once, then there is no need to type-case it to `list`

Or you can use it with the legendary list comprehensions as:

>>> ['{}{}'.format(x, y) for x, y in zip(a, b)]
['x1', 'y2', 'z3']

With format , you don't have to explicitly type-cast your int to str . Also it is simpler to change the format of your desired strings in the lists. For example:

>>> ['{} -- {}'.format(x, y) for x, y in zip(a, b)]
['x -- 1', 'y -- 2', 'z -- 3']

Here's a generalized solution to format n lists :

>>> my_lists = [
        ['a', 'b', 'c'],   # List 1
        [1, 2, 3],         # List 2
        # ...              # few more lists 
        ['x', 'y', 'z']    # List `N`
    ]

# Using `itertools.starmap`
>>> list(starmap(("{}"*len(my_lists)).format, zip(*my_lists)))
['a1x', 'b2y', 'c3z']

# Using list comprehension
>>> [('{}'*len(my_lists)).format(*x) for x in zip(*my_lists)]
['a1x', 'b2y', 'c3z']

Answer 3

You can try this one as well, based on @SilverSlash's solution, using the map function:

a = ['x','y','z']
b = [1,2,3]

c = list(map(''.join, zip(a, map(str, b))))
print(c)

Output:

['x1', 'y2', 'z3']