CODEWITHSUNDEEP
pythonpython-3.x
user13434360
user13434360

Reputation: 60

Creating python tuple with one int item

I was experimenting with tuple in python and stumbled upon this problem

t=tuple("2",) # works

but

t=tuple(1,) # fails

with error TypeError: 'int' object is not iterable

whereas

t=(1,) # works

Can anybody please explain why this is so?

Upvotes: 0

Views: 863

Answers (5)

Karl Knechtel
Karl Knechtel

Reputation: 61526

t=tuple(1,)

Because the parentheses here are for a function call, this is the same as t=tuple(1). So the exception is raised because you are requesting a tuple made out of all the elements that result from iterating over 1, but 1 is not the appropriate sort of thing for that.

t=(1,)

Now the `(1,) indicates a tuple.

Upvotes: 0

A. Teng Huat
A. Teng Huat

Reputation: 68

Its because in the first and second example, you're attempting to cast it into a tuple, while the last example you're creating a tuple.

t = tuple("a") # this is casting "a" into a tuple
t = ("a") # this is creating a tuple

As to why it works for string and not int, its because string is iterable.

some_string = "a"
print(tuple(some_string)) # ('a',)

some_other_string = "asd"
print(tuple(some_other_string)) # ('a', 's', 'd')

Upvotes: 1

chrislondon
chrislondon

Reputation: 12031

The tuple() function has a signature of tuple(iterable). It is not the same as creating a tuple using parentheses. In fact, the parentheses, while preferable, are optional.

The reason tuple("2") works is because strings are iterable in Python. You can do the following in python:

for i in "2":
    # ...

But you can't do the following:

for i in 1:
    # This causes a "TypeError: 'int' object is not iterable" error

If you wanted the int tuple in your example you could do it in the following ways:

t = tuple([1])
t = (1,)
t = 1,

Upvotes: 0

nocibambi
nocibambi

Reputation: 2421

As the TypeError also states, you can pass only iterables to a tuple.

A simple int item is not iterable, so that cannot work.

(1, ) works because 1, is already an iterable. Actually it is another tuple.

In a similar fashion, you can also adjust the failed tuple(1,) case to tuple((1, )) and it will also work.

Upvotes: 0

bigbounty
bigbounty

Reputation: 17368

The error message clearly explains why there's an error.

TypeError: 'int' object is not iterable

This means tuple() is expecting an iterable.

What data structures are iterable in python? --> list, set etc...

Hence, give an iterable like list or set to the tuple function. It will function. It's basically used for converting any iterable to tuple object.

So, the below works:

t = tuple([1,])

But in t = (1,) you already are creating a tuple object

Upvotes: 1

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