Add another tuple to a tuple of tuples

Question

I have the following tuple of tuples:

my_choices=(
         ('1','first choice'),
         ('2','second choice'),
         ('3','third choice')
)

and I want to add another tuple to the start of it

another_choice = ('0', 'zero choice')

How can I do this?

the result would be:

final_choices=(
             ('0', 'zero choice')
             ('1','first choice'),
             ('2','second choice'),
             ('3','third choice')
    )

Algorithm

That's a tuple of tuples, not a list of tuples. – Kostival

Answer 1

Build another tuple-of-tuples out of another_choice, then concatenate:

final_choices = (another_choice,) + my_choices

Alternately, consider making my_choices a list-of-tuples instead of a tuple-of-tuples by using square brackets instead of parenthesis:

my_choices=[
     ('1','first choice'),
     ('2','second choice'),
     ('3','third choice')
]

Then you could simply do:

my_choices.insert(0, another_choice)

Canvasback

"Alternately, consider making my_choices a list-of-tuples", the reason being lists are mutable, contrary to tuples. And if tuples are immutable, it's because this allows more efficient operations. – Chappell

Answer 2

Don't convert to a list and back, it's needless overhead. + concatenates tuples.

>>> foo = ((1,),(2,),(3,))
>>> foo = ((0,),) + foo
>>> foo
((0,), (1,), (2,), (3,))

Wanda

I thought you couldn't change tuples? – Traitorous

You can't---but you can redefine them :) – Wanda

You can't---but you can redefine them, actually what you're doing is assigning a new tuple object to the existing variable foo (which happens to already hold another tuple object, but that's irrelevant). So we need to understand "redefining" as a trivial assignment. +1 – Chappell

Answer 3

Alternatively, use the tuple concatenation

i.e.

final_choices = (another_choice,) + my_choices

Bullivant

Answer 4

You could use the "unpacking operator" (*) to create a new tuple

tpl = ((2, 11), (3, 10),)

tpl = (*tpl, (5, 8))

print(tpl) #prints ((2, 11), (3, 10), (5, 8))

Masaryk

Answer 5

What you have is a tuple of tuples, not a list of tuples. Tuples are read only. Start with a list instead.

>>> my_choices=[
...          ('1','first choice'),
...          ('2','second choice'),
...          ('3','third choice')
... ]
>>> my_choices.insert(0,(0,"another choice"))
>>> my_choices
[(0, 'another choice'), ('1', 'first choice'), ('2', 'second choice'), ('3', 'third choice')]

list.insert(ind,obj) inserts obj at the provided index within a list... allowing you to shove any arbitrary object in any position within the list.

Auspicate

Answer 6

my_choices=(
         ('1','first choice'),
         ('2','second choice'),
         ('3','third choice')
)

new=('0','zero choice')

l=[item for item in my_choices]
l.insert(0,new)
my_choices=tuple(l)
print(my_choices)

1. create a list from element of my_choices tuple
2. Now you can insert the new tuple element at the first position (index 0)
3. Create a new tuple from list named list and assign it to "my_choices"
4. Print my_choices variable (a tuple of tuples)

Bellwether

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