python add to a list of tuples

Question

I have the following list of tuple:

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')
    )

Answer 1

What you have 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.

Answer 2

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)

Answer 3

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,))

Answer 4

Alternatively, use the tuple concatenation

i.e.

final_choices = (another_choice,) + my_choices