Tuple in Python

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In this blog, we are going to discuss the tuple data structure of python.

A tuple is a collection which is immutable, we cannot change the elements of a tuple once it is assigned. It allows duplicate members i.e. (1, 1) is allowed.

Any set mutiple comma-separated symbols written default to tuples.

>>> x, y = 1, 2

Dictionaries have a method called items that returns a list of tuples, where each tuple is a key-value pair.

>> d = {‘a’: 10, ‘b’: 1, ‘c’: 22}
>> t = d.items()
> print(t)
[(‘a’, 10), (‘c’, 22), (‘b’, 1)]

DECLARE TUPLE

Tuple can be declared using round brackets or tuple constructor.
>>> emptytuple= ()
>>> emptylist
()
>>> type(emptytuple)
>>> emptytuple = tuple()
>>> emptytuple
[]
>>> tup = (1) # creating tuple with single element requires “,” in the end
>>> tup
1
>>> type(tup)
>>> tup = (1,)
>>> type(tup)
The syntax of tuple() constructor is:
tuple([iterable])
>>> tup = tuple(1,2)
Traceback (most recent call last):
File “”, line 1, in
TypeError: tuple() takes at most 1 argument (2 given)
>>> tup = tuple((1,2))
>>> tup
(1, 2)
>>> tup = tuple([1,2]) # creating tuple from list
>>> tup
(1, 2)

ACCESS ELEMENTS OF TUPLE

>>> tup = (1, 2, 3)
>>> tup[0]
1
>>> tup[-1] # using negative indexing
3
>>> tup[-3]
1
>>> tup[-7]
Traceback (most recent call last):
File “”, line 1, in
IndexError: tuple index out of range

ADD ELEMENTS TO TUPLE

>>> tup = (1, 2, 3, 4)
>>> tup.insert(0, 10)

Tuples are immutable.

MODIFYING ELEMENTS OF TUPLE

>>> tup = (1, 2, 3, 4)
>>> tup[0] = 7
>>> tup
Traceback (most recent call last):
File “”, line 1, in
TypeError: ‘tuple’ object does not support item assignment

You can’t modify the elements of tuples because tuples are immutable.

ITERATE ITEMS OF TUPLE

>>> tup = (1, 2, 3, 4)
>>> for item in tup:
… print(item)
1
2
3
4

OPERATORS ON TUPLE

>>> tup = (1, 2, 3, 4)
>>> tupOne = (4, 5)
>>> tup + tupOne # tuple concatenation it will create new tuple
(1, 2, 3, 4, 4, 5)
>>> tupOne * 3 # new tuple will be created
(4, 5, 4, 5, 4, 5)

DELETING ELEMENTS OF TUPLE

>>> tup = (1, 2, 3, 4)
>>> del tup[0]
Traceback (most recent call last):
File “”, line 1, in
TypeError: ‘tuple’ object doesn’t support item deletion

FUNCTIONS ON TUPLE

>>> tup = (1, 2, 3, 4, 5, 5)
>>> tup.index(3)
2
>>> tup.count(5)
2
>>> max(tup)
5
>>> min(tup)
1

CHECK EXISTENCE OF ITEM IN TUPLE

>>> tup = (1, 2, 3, 4, 5, 5)
>>> 1 in tup
True
>>> 7 in tup
False

DELETE TUPLE

>>> tup = (1, 2, 3, 4, 5, 5)
>>> del tup

ACCESSING ITEMS OF NESTED TUPLE

>>> old_tup
((1, 30, 3), (4, 5, 6), (7, 8, 9), (4, 4, 4), (4, 4, 4))
>>> old_tup[2][2]
9

LIST VS TUPLE

  • Tuples have structure while lists have order.
>>> tup = (1, 2)
>>> tup.sort()
Traceback (most recent call last):
File “”, line 1, in
AttributeError: ‘tuple’ object has no attribute ‘sort’
>>> tup.reverse()
Traceback (most recent call last):
File “”, line 1, in
AttributeError: ‘tuple’ object has no attribute ‘reverse’

You can’t modify the structure of tuple.

  • Tuples are faster than list. Tuples are stored in a single block of memory. Tuples are immutable so, It doesn’t require extra space to store new objects. Lists are allocated in two blocks: the fixed one with all the Python object information and a variable sized block for the data. This is the reason why creating a tuple is faster than List. Tuples load as a whole while in lists individual elements get loaded.
  • Tuples can store the elements directly inside the struct, lists on the other hand need a layer of indirection (it stores a pointer to the elements).
a = tuple(range(1000))
b = list(range(1000))
a.__sizeof__() # 8024
b.__sizeof__() # 9088
  • Tuple is hashable while list is not. Hash functions return the hash value of the object, if it has one.
>>> tup = (1, 2)
>>> hash(tup)
3713081631934410656
>>> list = [1, 2]
>>> hash(list)
Traceback (most recent call last):
File “”, line 1, in
TypeError: unhashable type: ‘list’
  • Tuples can be used as a key in dictionary as they are immutable while lists cannot be.
>>> list = [1, 2]
>>> tup = (1, 2)
>>> dict = {list: 1}
Traceback (most recent call last):
File “”, line 1, in
TypeError: unhashable type: ‘list’
>>> dict = {tup: 1}
>>> dict
{(1, 2): 1}

Thanks for reading!!

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