List comprehension: Returning two (or more) items for each item

python list-comprehension
Hashmush picture Hashmush · Aug 8, 2012 · Viewed 30.5k times · Source

Is it possible to return 2 (or more) items for each item in a list comprehension?

What I want (example):

[f(x), g(x) for x in range(n)]

should return [f(0), g(0), f(1), g(1), ..., f(n-1), g(n-1)]

So, something to replace this block of code:

result = list()
for x in range(n):
    result.add(f(x))
    result.add(g(x))

Answer

ninjagecko picture ninjagecko · Aug 8, 2012

Double list comprehension:

[f(x) for x in range(5) for f in (f1,f2)]

Demo:

>>> f1 = lambda x: x
>>> f2 = lambda x: 10*x

>>> [f(x) for x in range(5) for f in (f1,f2)]
[0, 0, 1, 10, 2, 20, 3, 30, 4, 40]

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