Sort a list in Python without sort Function

Python Lists are a type of data structure that is mutable in nature. This means that we can modify the elements in the list. We can sort a list in Python using the inbuilt list sort() function. But in this article, we will learn how we can sort a list in a particular order without using the list sort() method.

Sort a List Without Using Sort Function in Python

Sorting is nothing but arranging the elements of a list in a particular order and this order can be either increasing or decreasing in nature. We can sort a list in Python without using the list sort() function by using nested for loops. Let us see a few examples, of how we can sort a list without the sort() function.

Sort a List in Ascending Order Without using an Extra Variable

In this example, we will have a list and we will sort it in ascending order using just the nested loop. We will compare each element in the list one by one and swap it.

Python3

#Python program to print a list
# without using the sort() function
# without an extra variable

l1=[76, 23, 45, 12, 54, 9]
print("Original List:", l1)

# sorting list using nested loops
for i in range(0, len(l1)):
    for j in range(i+1, len(l1)):
        if l1[i] >= l1[j]:
            l1[i], l1[j] = l1[j],l1[i]

# sorted list
print("Sorted List", l1)

Output:

Original List: [76, 23, 45, 12, 54, 9]
Sorted List [9, 12, 23, 45, 54, 76]

Sort a List in Ascending Order by Using an extra variable

In this example, we will have a list and we will sort it in ascending order by using the nested for loop and a temporary variable.

Python3

#Python program to print a list
# without using the sort() function
# using an extra variable

l1=[76,23,45,12,54,9]
print("Original List:", l1)

# sorting list using nested loops
for i in range(0, len(l1)):
    for j in range(i+1, len(l1)):
        if l1[i] >= l1[j]:
            # temporary variable
            temp = l1[i]
            l1[i] = l1[j]
            l1[j] = temp

# sorted list
print("Sorted List", l1)

Output:

Original List: [76, 23, 45, 12, 54, 9]
Sorted List [9, 12, 23, 45, 54, 76]

Sort a List in Descending Order

In this example, instead of a predefined list, we will take a list whose values are provided by the user. Then we will sort the list in descending order without using an extra variable.

Python3

# create an empty list
l1 = []
n = int(input("enter number of elements required: "))
# creating a list using loop
for i in range(0, n):
    element = int(input())
    # appending elements to the list
    l1.append(element)
print("Original List:", l1)

# sorting in decending
for i in range(0, len(l1)):
  for j in range(i+1, len(l1)):
    if l1[i] <= l1[j]:
      l1[i], l1[j] = l1[j], l1[i]

# sorted list
print("Sorted List", l1)

Output:

enter number of elements required: 6
76
23
45
12
54
9
Original List: [76, 23, 45, 12, 54, 9]
Sorted List [76, 54, 45, 23, 12, 9]