Python idiom to return first item or None

Question

I'm calling a bunch of methods that return a list. The list may be empty. If the list is non-empty, I want to return the first item; otherwise, I want to return None. This code works:

def main():
    my_list = get_list()
    if len(my_list) > 0:
        return my_list[0]
    return None

but it seems to me that there should be a simple one-line idiom for doing this. Is there?

Answer 1

Python 2.6+

next(iter(your_list), None)

If your_list can be None:

next(iter(your_list or []), None)

Python 2.4

def get_first(iterable, default=None):
    if iterable:
        for item in iterable:
            return item
    return default

Example:

x = get_first(get_first_list())
if x:
    ...
y = get_first(get_second_list())
if y:
    ...

Another option is to inline the above function:

for x in get_first_list() or []:
    # process x
    break # process at most one item
for y in get_second_list() or []:
    # process y
    break

To avoid break you could write:

for x in yield_first(get_first_list()):
    x # process x
for y in yield_first(get_second_list()):
    y # process y

Where:

def yield_first(iterable):
    for item in iterable or []:
        yield item
        return