Ignore python multiple return value

Question

Say I have a Python function that returns multiple values in a tuple:

def func():
    return 1, 2

Is there a nice way to ignore one of the results rather than just assigning to a temporary variable? Say if I was only interested in the first value, is there a better way than this:

x, temp = func()

Answer 1

You can use x = func()[0] to return the first value, x = func()[1] to return the second, and so on.

Answer 2

One common convention is to use a "_" as a variable name for the elements of the tuple you wish to ignore. For instance:

def f():
    return 1, 2, 3

_, _, x = f()

Answer 3

Three simple choices.

Obvious

x, _ = func()

x, junk = func()

Hideous

x = func()[0]

And there are ways to do this with a decorator.

def val0( aFunc ):
    def pick0( *args, **kw ):
        return aFunc(*args,**kw)[0]
    return pick0

func0= val0(func)

Answer 4

Remember, when you return more than one item, you're essentially returning a list-like object. So you can do things like this:

def func():
    return 1, 2

print func()[0] # prints 1
print func()[1] # prints 2

Answer 5

This seems like the best choice to me:

val1, val2, ignored1, ignored2 = some_function()

It's not cryptic or ugly (like the func()[index] method), and clearly states your purpose.

Answer 6

If you're using Python 3, you can you use the star before a variable (on the left side of an assignment) to have it be a list in unpacking.

# Example 1: a is 1 and b is [2, 3]

a, *b = [1, 2, 3]

# Example 2: a is 1, b is [2, 3], and c is 4

a, *b, c = [1, 2, 3, 4]

# Example 3: b is [1, 2] and c is 3

*b, c = [1, 2, 3]

# Example 4: a is 1 and b is []

a, *b = [1]