Variables can be of the datatype tuple. A tuple is collection that cannot be modified.

It differs from a list, in that lists can be changed or modified after creation.
A tuple is defined using parenthesis ( and ) instead of [ and ] that a list uses.

If you want to change the data during program execution, use a list instead of a tuple.

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Python tuple

A tuple is an immutable sequence type. A tuple is a sequence, but its values cannot be altered.

The values of a tuple cannot change. This is very important, because this is the only difference between a list.

To create a tuple, all you need to do is define a set of comma-separated values between the parenthesis.

An empty tuple would be defined as:

tup1 = ()

be careful with parenthesis, () is a tuple and [] is a list and {} a dictionary

A tuple with one item ( a comma is needed in the end ):

x = (1,) 

x = (1,2,3,4) 

You can create all kinds of tuples:

t1 = ('physics', 'chemistry', 'geography', 'history')
t2 = (1, 2, 3, 4, 5 )
t3 = ("a", "b", "c", "d")

Note: Even if your tuple has only one element, the comma is needed between the parenthesis.

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Accessing tuples

To access individual elements, we use square brackets. To print the first element (Python starts counting from zero):

print(x[0]) 

print(x[1]) 

You can access tuples both in the interpreter and during code execution.
In the interpreter python, you can type commands.

Lets create a tuple

>>> t1 = ('coffee','tea','orange juice','lemonade')

Then output some elements

>>> t1[0]
'coffee'
>>> t1[1]
'tea'

And why not try to change a value

>>> t1[1] = 'water'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>>

Remember, the contents of a tuple cannot be changed after creation.

To print the last element, you can count from the back using the minus sign.

print(x[-1]) 

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Tuple Unpacking

You can unpack a tuple. A package tuple object has more than one value like:

>>> t = (1,2,3)

To unpack the tuple you can do this:

>>> x,y,z = t

Then each variable (x,y,z) will contain one of the tuples values:

>>> x
1
>>> y
2
>>> z
3
>>>

When unpacking, the number of variables must match the number of values in the tuple:

>>> t = (1,2,3)
>>> x,y = t
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: too many values to unpack (expected 2)
>>>

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Tuple assignment

If you define a tuple, Python allows the parenthesis to be left out. In Python these are the same:

>>> t = (1,2,3)
>>> t = 1,2,3

So you can do unpacking like this:

>>> t = 1,2,3
>>> t
(1, 2, 3)
>>> 
>>> x,y,z = t
>>> x
1
>>> y
2
>>> z
3
>>>

So it works both if parenthesis are written or left out. For clarity, you could add them.

When in doubt, you can always call type().

>>> type(t)
<class 'tuple'>
>>>

Python tuple append

Once defined, the contents of a tuple cannot be changed.

>>> t = (1,2,3)
>>> t.append(4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'append'
>>>

That is by design. If you want to append values, you should use a list.

Note: Tuples cannot be changed. But what you can do, is create a new tuple and overwrite it.

However, you can add a tuple to a tuple:

>>> t = t + (4,)
>>> t
(1, 2, 3, 4)
>>>

A new element has been appended at the end of the tuple, by appending two tuples.

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Python tuple insert

Start with a tuple, like this:

>>> t = (1,2,4,5)

To insert a new tuple, create three tuples and the tuple to insert will go in the middle.
So you can use tuple slicing [start:end] and combine.

The example below shows how a new tuple is created with a new element in the middle:

>>> t = t[0:2] + (3,) + t[2:4]
>>> t
(1, 2, 3, 4, 5)

Python tuple modify

The contents of a tuple cannot be changed. If you try it will throw an TypeError.

>>> t[1] = 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>>

You can get around this by creating a new tuple.

>>> t = (1,2,3,4,5)
>>> t = t[0:1] + (0,) + t[2:]
>>> t
(1, 0, 3, 4, 5)
>>>

Python tuple delete

An element cannot be deleted. You can only create a new tuple without that element.

If you have this tuple:

>>> t = (1,2,3,4,5)

You can create a new one using slicing:

>>> # Create new tuple
>>> t = t[0:1] + t[2:]
>>> t
(1, 3, 4, 5)
>>>

If you want to change the contents of a tuple (append, delete, modify,…) you should use a list instead.

Python tuple to list

To convert a tuple to a list, call the list() function.

>>> # create tuple
... t = (1,2,3,4,5)

>>> # convert tuple to list
>>> mylist = list(t)

If you output mylist, you’ll see its a list:

>>> mylist
[1, 2, 3, 4, 5]
>>>

You can see the difference between lists and tuples by their parenthesis.

• Tuples use ()
• lists uses [].

Python list to tuple

A list can be converted to a tuple by calling the tuple() function:

>>> t = tuple(mylist)

Variable t is then a tuple:

>>> t
(1,2,3,4,5)

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