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+---
+id: 033-insertion-sort-python.md
+title: Insertion Sort in Python
+tags:
+  - python
+  - insertion sort
+  - sorting
+  - algorithms
+date: 2021-10-11 17:30:00 -0800
+keywords: python, sorting, algorithms, insertion, sort
+categories:
+  - python
+cover: ../../images/categories/python.png
+author: Ryan Lim
+meta-description: insertion sort in python
+---
+
+# Insertion Sort in Python
+
+[Insertion Sort](https://en.wikipedia.org/wiki/Insertion_sort) is type of [sorting algorithm](https://en.wikipedia.org/wiki/Sorting_algorithm) that is relatively simple to implement. It does not have the best runtime, i.e. `O(n^2)`, compared to more advanced sorting algorithms such as [quicksort](https://en.wikipedia.org/wiki/Quicksort) or [merge sort](https://en.wikipedia.org/wiki/Merge_sort) but is a good starting sorting algorithm to learn. It can be used to sort smaller arrays consisting of strings or numbers.
+
+## Pseudocode
+
+Here is the pseudocode of insertion code (from [wikipedia](https://en.wikipedia.org/wiki/Insertion_sort#Algorithm)):
+
+```
+i ← 1
+while i < length(A)
+    j ← i
+    while j > 0 and A[j-1] > A[j]
+        swap A[j] and A[j-1]
+        j ← j - 1
+    end while
+    i ← i + 1
+end while
+```
+
+The general idea behind it is to iterate through the array from beginning to end and swaps each element from the current element to the beginning of the array if a "greater" prior element is found compare to the current element.
+
+## Python Implementation
+
+Without further ado, here is my Python (3) implementation of it:
+
+```python
+def insertion_sort(array):
+    for i in range(1, len(array)):
+        j = i
+        while j > 0 and array[j - 1] > array[j]:
+            temp = array[j - 1]
+            array[j - 1] = array[j]
+            array[j] = temp
+            j -= 1
+    return array
+```
+
+Thanks for reading, any comment or feedback is most welcome!