# Algorithm: How to Bubble Sort Integer/String Array in Python

Hi There! This ‘Concept-into-Code’ blog post is the first in a series where I will try to explain concepts into code in the simplest ways that I can.

This is my first blog, trying to do simple and short about particular concepts that I’m learning about and share it with you.

**Introduction to Bubble Sort**

**Bubble Sort** is the simplest sorting algorithm. It is used to sort elements in Ascending order or Descending order. Its name resembles the way the Algorithm works: with every new pass, the largest element in the list “bubbles up” from the list.

Bubble sort consists of multiple passes through a list. During each pass, the algorithm compares adjacent elements and swap them if they are unsorted depending on their value and intended order.

Basically, Bubble sort performs three simple tasks:

Repeatedly going through the list of elements to sort.

Comparing adjacent elements with each other and sort them.

Swapping them around if they are not in the intended order.

# Bubble Sort pseudocode

```
bubbleSort(inputArray)
n = length(inputArray)
for (1= 0 until n)
for (j = 0 until n-i-1)
if(array[j] > array[j + 1])
swap(array, j, j+1)
```

In this pseudocode, n is the length of our array. To ensure that our entire list is sorted we need to do n — 1 pass on our list. If we had a list of 10 items, we would need to compare the second element of our list (at position 1 in the array) and keep going through it 9 times until we have sorted the entire list. A sorted bubble is building at the end of the list, this is why we need to make n — 1 pass on our list.

In our, if statements, we are comparing the number in our array at position j with the number at position j + 1 (the adjacent number in our list).

To properly analyze how this algorithm works, here we are considering an Array of Strings [‘g’, ‘i’, ‘a’, ‘k’, ‘e’], we can also use an array of integers. Assume you’re using bubble_sort() from above. Here’s a figure illustrating what the array looks like at each iteration of the algorithm:

The above-unsorted list is not the worst case, the worst-case unsorted list would be a list in descending order. For such a list, that contains *n* elements, we need to perform (n-1) swaps for it to be sorted in ascending order. Observe how for the first round you need to sort all of the *n *elements, while on the second round you sort *(n-1) *elements and so on and so forth.

**Implementing Bubble Sort in Python**

Below is implementation to sort an Integer / String Array using Bubble sort in Python:

```
def bubble_sort(arr):
n = len(arr)
for i in range(n):
for j in range(n - i - 1):
if arr[j] > arr[j + 1]:
# sorting by using simultaneous assignment in python
arr[j], arr[j + 1] = arr[j + 1], arr[j]
arr1 = [7, 4, 3, 6, 2]
arr2 = ['g', 'i', 'a', 'k', 'e']
print('Before sorting an Integer Array: {}'.format(arr1))
bubble_sort(arr1)
print('After sorting an Integer Array: {}'.format(arr1))
print('Before sorting an String Array: {}'.format(arr2))
bubble_sort(arr2)
print('After sorting an String Array: {}'.format(arr2))
```

**Output:**

```
Before sorting an Integer Array: [7, 4, 3, 6, 2]
After sorting an Integer Array: [2, 3
```