Working with Tuples in Python 3

Working with Tuples

Unlike Lists, Tuples are immutable lists, that cannot be modified. A Tuple is created by placing all the items (elements) inside () parenthesis, separated by commas. A Tuple can store data in the form of a string literal, integer or any allowed data type in Python. A tuple can have heterogeneous data items, a tuple can have string and list as data items as well. You can access elements of the tuple using an index. Traverse a tuple using the loop. Nested tuples can be created.  Like Lists, we can use slicing with Tuples. There are different methods or operations that can be performed on tuples such as Changing the elements of a tuple, delete operation, membership test, etc.

First of all, we will start with listing difference between Tuples and Lists

Difference b/w List & Tuple 

Initializing and Traversing a Tuple using index & Loop

In the below code, we will demonstrate, how to initialize a tuple and traverse the tuple using a for loop.

Code: 

a = (1, 2, 3, 4, 5, 6)

a_length = len(a)
for i in range(a_length):
    print(a[i])

Output: 

1
2
3
4
5
6

Negative indexes in tuples

Similar to list and strings we can use negative indexes to access the tuple elements from the end. -1 to access the last element, -2 to access second last and so on.

Using Positive index 0 to n-1 from first to the last element. Using Negative index -1 to -n from last element to the first.

In the below code, we will demonstrate, how to initialize a tuple and traverse the tuple using a for loop.

Code: 

a = (1, 2, 3, 4, 5, 6)

a_length = -len(a)

for i in range(-1, a_length-1, -1):
    print(a[i])

Output: 

6
5
4
3
2
1

Using Nested tuples

Code: 

a = (1, 2, 3) # 1Dimensional TUPLE of order 1 by 3
b = (5, 6, 6)  # 1Dimensional TUPLE of order 1 by 3
c = (102, 5, -7) # 1Dimensional TUPLE of order 1 by 3

x1 = ((1, 2, 4), (2, 4, 5), (0, 0, 0))  # 2Dimensional TUPLE of order 3 by 3
x2 = ((5, 6, 7), (11, 14, 45), (90, 87, 73))  # 2Dimensional TUPLE 3 by 3
x3 = ((7, 11, 19), (15, 154, 415), (190, 807, 723)) # 2Dimensional TUPLE 3 by 3


d = (a, b, c) # 2Dimensional TUPLE of order 3 by 3
#D1 D2
D1 = len(d)
D2 = len(d[0])

for i in range(D1):
    for j in range(D2):
        print(d[i][j], end=" ")
    print("\t")

print("\n")
x = [x1, x2, x3] # 3Dimensional TUPLE of order 3 by 3 by 3
#X1 X2
X1 = len(x)
X2 = len(x[0])
X3 = len(x[0][0])

for i in range(X1):
    for j in range(X2):
        for k in range(X3):
            print(x[i][j][k], end=" ")
        print("\t")
    print("\n")

Output: 

1 2 3
5 6 6
102 5 -7


1 2 4
2 4 5
0 0 0


5 6 7
11 14 45
90 87 73


7 11 19
15 154 415
190 807 723

Changing & Deleting Elements of a Tuple

We cannot change the elements of a tuple because tuple itself is immutable. However, we can change the elements of nested items that are mutable. For example, in the following code, we are changing the element of the list which is present inside the tuple. List items are mutable that’s why it is allowed.

Tuple elements are immutable which also means that we cannot delete the elements of a tuple. However, deleting entire tuple is possible.

Code: 

a = (1, 2, 3, ["I", "Love", "Python"], 4, 5, 6)

print(a)

a[3][0], a[3][1], a[3][2] = "You", "Hate", "Python"
print(a)

del a
#You will get error, as the tuple is deleted
print(a)

Output: 

(1, 2, 3, ['I', 'Love', 'Python'], 4, 5, 6)
(1, 2, 3, ['You', 'Hate', 'Python'], 4, 5, 6)
Traceback (most recent call last):
  File "practise.py", line 10, in <module>
    print(a)
NameError: name 'a' is not defined

Slicing in Tuple

Slices work on Tuple just as with strings and lists, and can also be used to change sub-parts of the Tuple.

Code: 

Nordic_Country_Tuple = ("FINLAND", "ICELAND", "NORWAY", "DENMARK", "SWEDEN", "FAROE ISLANDS")

print(Nordic_Country_Tuple[0:1])

print(Nordic_Country_Tuple[0:2])

print(Nordic_Country_Tuple[0:4])

# displaying entire tuple
print(Nordic_Country_Tuple[:])

print(Nordic_Country_Tuple[4:-1])

Output: 

('FINLAND',)
('FINLAND', 'ICELAND')
('FINLAND', 'ICELAND', 'NORWAY', 'DENMARK')
('FINLAND', 'ICELAND', 'NORWAY', 'DENMARK', 'SWEDEN', 'FAROE ISLANDS')
('SWEDEN',)

Membership Test in Tuples

in: Checks whether an element exists in the specified tuple.
not in: Checks whether an element does not exist in the specified tuple.

Code: 

Nordic_Country_Tuple = ("FINLAND", "ICELAND", "NORWAY", "DENMARK", "SWEDEN", "FAROE ISLANDS")

print("FINLAND" in Nordic_Country_Tuple)

print("ICELAND" in Nordic_Country_Tuple)

print("FAROE ISLANDS" not in Nordic_Country_Tuple)

print("DENMARK" not in Nordic_Country_Tuple)

Output: 

True
True
False
False