Getting one value from a tuple

Question

Is there a way to get one value from a tuple in Python using expressions?

def tup():
  return (3, "hello")

i = 5 + tup()  # I want to add just the three

I know I can do this:

(j, _) = tup()
i = 5 + j

But that would add a few dozen lines to my function, doubling its length.

Larousse

The _ is also just a variable. It's just often used to assign value to it that can be discarded. But theoretically you can get the value from _ – Ambrotype

Answer 1

You can write

i = 5 + tup()[0]

Tuples can be indexed just like lists.

The main difference between tuples and lists is that tuples are immutable - you can't set the elements of a tuple to different values, or add or remove elements like you can from a list. But other than that, in most situations, they work pretty much the same.

Hydraulic

Answer 2

For anyone in the future looking for an answer, I would like to give a much clearer answer to the question.

# for making a tuple
my_tuple = (89, 32)
my_tuple_with_more_values = (1, 2, 3, 4, 5, 6)

# to concatenate tuples
another_tuple = my_tuple + my_tuple_with_more_values
print(another_tuple)
# (89, 32, 1, 2, 3, 4, 5, 6)

# getting a value from a tuple is similar to a list
first_val = my_tuple[0]
second_val = my_tuple[1]

# if you have a function called my_tuple_fun that returns a tuple,
# you might want to do this
my_tuple_fun()[0]
my_tuple_fun()[1]

# or this
v1, v2 = my_tuple_fun()

Hope this clears things up further for those that need it.

Cuda

Thanks for the update. For completeness, you may want to add the use of the underscore as 'dummy' placeholder in tuple unpacking. – Superman

Answer 3

General

Single elements of a tuple a can be accessed -in an indexed array-like fashion-

via a[0], a[1], ... depending on the number of elements in the tuple.

Example

If your tuple is a=(3,"a")

• a[0] yields 3,
• a[1] yields "a"

Concrete answer to question

def tup():
  return (3, "hello")

tup() returns a 2-tuple.

In order to "solve"

i = 5 + tup()  # I want to add just the three

you select the 3 by:

tup()[0]    # first element

so all together:

i = 5 + tup()[0]

Alternatives

Go with namedtuple that allows you to access tuple elements by name (and by index). Details are at https://docs.python.org/3/library/collections.html#collections.namedtuple

>>> import collections
>>> MyTuple=collections.namedtuple("MyTuple", "mynumber, mystring")
>>> m = MyTuple(3, "hello")
>>> m[0]
3
>>> m.mynumber
3
>>> m[1]
'hello'
>>> m.mystring
'hello'

Within