Python idiom to return first item or None

Question

I\'m sure there\'s a simpler way of doing this that\'s just not occurring to me.

I\'m calling a bunch of methods that return a list. The list may be empty. If the

Answer 1

Using the and-or trick:

a = get_list()
return a and a[0] or None

Answer 2

my_list[0] if len(my_list) else None

Answer 3

The best way is this:

a = get_list()
return a[0] if a else None

You could also do it in one line, but it's much harder for the programmer to read:

return (get_list()[:1] or [None])[0]

Answer 4

My use case was only to set the value of a local variable.

Personally I found the try and except style cleaner to read

items = [10, 20]
try: first_item = items[0]
except IndexError: first_item = None
print first_item

than slicing a list.

items = [10, 20]
first_item = (items[:1] or [None, ])[0]
print first_item

Answer 5

How about this:

(my_list and my_list[0]) or None

Note: This should work fine for lists of objects but it might return incorrect answer in case of number or string list per the comments below.

Answer 6

Not sure how pythonic this is but until there is a first function in the library I include this in the source:

first = lambda l, default=None: next(iter(l or []), default)

It's just one line (conforms to black) and avoids dependencies.