How do I call a function twice or more times consecutively?

Is there a short way to call a function twice or more consecutively in Python? For example:

do()
do()
do()

maybe like:

3*do()

Solution 1:

I would:

for _ in range(3):
    do()

The _ is convention for a variable whose value you don't care about.

You might also see some people write:

[do() for _ in range(3)]

however that is slightly more expensive because it creates a list containing the return values of each invocation of do() (even if it's None), and then throws away the resulting list. I wouldn't suggest using this unless you are using the list of return values.

Solution 2:

You could define a function that repeats the passed function N times.

def repeat_fun(times, f):
    for i in range(times): f()

If you want to make it even more flexible, you can even pass arguments to the function being repeated:

def repeat_fun(times, f, *args):
    for i in range(times): f(*args)

Usage:

>>> def do():
...   print 'Doing'
... 
>>> def say(s):
...   print s
... 
>>> repeat_fun(3, do)
Doing
Doing
Doing
>>> repeat_fun(4, say, 'Hello!')
Hello!
Hello!
Hello!
Hello!

Solution 3:

Three more ways of doing so:

(I) I think using map may also be an option, though is requires generation of an additional list with Nones in some cases and always needs a list of arguments:

def do():
    print 'hello world'

l=map(lambda x: do(), range(10))

(II) itertools contain functions which can be used used to iterate through other functions as well https://docs.python.org/2/library/itertools.html

(III) Using lists of functions was not mentioned so far I think (and it is actually the closest in syntax to the one originally discussed) :

it=[do]*10
[f() for f in it]

Or as a one liner:

[f() for f in [do]*10]

Solution 4:

A simple for loop?

for i in range(3):
  do()

Or, if you're interested in the results and want to collect them, with the bonus of being a 1 liner:

vals = [do() for _ in range(3)]