A tuple in Python is similar to a list. The difference between the two is that we cannot change the elements of a tuple once it is assigned whereas, in a list, elements can be changed.
A tuple is created by placing all the items (elements) inside parentheses (), separated by commas. The parentheses are optional, however, it is a good practice to use them.
()
A tuple can have any number of items and they may be of different types (integer, float, list, string, etc.).
# Empty tuple my_tuple = () print(my_tuple) # Output: () # Tuple having integers my_tuple = (1, 2, 3) print(my_tuple) # Output: (1, 2, 3) # tuple with mixed datatypes my_tuple = (1, "Hello", 3.4) print(my_tuple) # Output: (1, "Hello", 3.4) # nested tuple my_tuple = ("mouse", [8, 4, 6], (1, 2, 3)) # Output: ("mouse", [8, 4, 6], (1, 2, 3)) print(my_tuple)
A tuple can also be created without using parentheses. This is known as tuple packing.
my_tuple = 3, 4.6, "dog" print(my_tuple) # Output: 3, 4.6, "dog" # tuple unpacking is also possible a, b, c = my_tuple print(a) # 3 print(b) # 4.6 print(c) # dog
Creating a tuple with one element is a bit tricky.
Having one element within parentheses is not enough. We will need a trailing comma to indicate that it is, in fact, a tuple.
my_tuple = ("hello") print(type(my_tuple)) # <class 'str'> # Creating a tuple having one element my_tuple = ("hello",) print(type(my_tuple)) # <class 'tuple'> # Parentheses is optional my_tuple = "hello", print(type(my_tuple)) # <class 'tuple'>
There are various ways in which we can access the elements of a tuple.
We can use the index operator [] to access an item in a tuple where the index starts from 0.
[]
So, a tuple having 6 elements will have indices from 0 to 5. Trying to access an element outside of tuple (for example, 6, 7,...) will raise an IndexError.
IndexError
The index must be an integer; so we cannot use float or other types. This will result in TypeError.
TypeError
Likewise, nested tuples are accessed using nested indexing, as shown in the example below.
my_tuple = ('p','e','r','m','i','t') print(my_tuple[0]) # 'p' print(my_tuple[5]) # 't' # IndexError: list index out of range # print(my_tuple[6]) # Index must be an integer # TypeError: list indices must be integers, not float # my_tuple[2.0] # nested tuple n_tuple = ("mouse", [8, 4, 6], (1, 2, 3)) # nested index print(n_tuple[0][3]) # 's' print(n_tuple[1][1]) # 4
Python allows negative indexing for its sequences.
The index of -1 refers to the last item, -2 to the second last item and so on.
my_tuple = ('p','e','r','m','i','t') # Output: 't' print(my_tuple[-1]) # Output: 'p' print(my_tuple[-6])
We can access a range of items in a tuple by using the slicing operator - colon ":".
my_tuple = ('p','r','o','g','r','a','m','i','z') # elements 2nd to 4th # Output: ('r', 'o', 'g') print(my_tuple[1:4]) # elements beginning to 2nd # Output: ('p', 'r') print(my_tuple[:-7]) # elements 8th to end # Output: ('i', 'z') print(my_tuple[7:]) # elements beginning to end # Output: ('p', 'r', 'o', 'g', 'r', 'a', 'm', 'i', 'z') print(my_tuple[:])
Slicing can be best visualized by considering the index to be between the elements as shown below. So if we want to access a range, we need the index that will slice the portion from the tuple.
Unlike lists, tuples are immutable.
This means that elements of a tuple cannot be changed once it has been assigned. But, if the element is itself a mutable datatype like list, its nested items can be changed.
We can also assign a tuple to different values (reassignment).
my_tuple = (4, 2, 3, [6, 5]) # TypeError: 'tuple' object does not support item assignment # my_tuple[1] = 9 # However, item of mutable element can be changed my_tuple[3][0] = 9 # Output: (4, 2, 3, [9, 5]) print(my_tuple) # Tuples can be reassigned my_tuple = ('p','r','o','g','r','a','m','i','z') # Output: ('p', 'r', 'o', 'g', 'r', 'a', 'm', 'i', 'z') print(my_tuple)
We can use + operator to combine two tuples. This is also called concatenation.
+
We can also repeat the elements in a tuple for a given number of times using the * operator.
*
Both + and * operations result in a new tuple.
# Concatenation # Output: (1, 2, 3, 4, 5, 6) print((1, 2, 3) + (4, 5, 6)) # Repeat # Output: ('Repeat', 'Repeat', 'Repeat') print(("Repeat",) * 3)
As discussed above, we cannot change the elements in a tuple. That also means we cannot delete or remove items from a tuple.
But deleting a tuple entirely is possible using the keyword del.
my_tuple = ('p','r','o','g','r','a','m','i','z') # can't delete items # TypeError: 'tuple' object doesn't support item deletion # del my_tuple[3] # Can delete an entire tuple del my_tuple # NameError: name 'my_tuple' is not defined print(my_tuple)
Methods that add items or remove items are not available with tuple. Only the following two methods are available.
count(x)
index(x)
Some examples of Python tuple methods:
my_tuple = ('a','p','p','l','e',) print(my_tuple.count('p')) # Output: 2 print(my_tuple.index('l')) # Output: 3
We can test if an item exists in a tuple or not, using the keyword in.
in
my_tuple = ('a','p','p','l','e',) # In operation # Output: True print('a' in my_tuple) # Output: False print('b' in my_tuple) # Not in operation # Output: True print('g' not in my_tuple)
Using a for loop we can iterate through each item in a tuple.
for
# Output: # Hello John # Hello Kate for name in ('John','Kate'): print("Hello",name)
Since tuples are quite similar to lists, both of them are used in similar situations as well.
However, there are certain advantages of implementing a tuple over a list. Below listed are some of the main advantages:
