Selection Sort in Python

Now that we understand the logic behind Selection Sort, let’s write the code to implement it.

We’ll use the same example list:

We’ll create a function called selection_sort that takes a list as input:

def selection_sort(my_list):

# Loop through each index except the last one

for i in range(len(my_list) – 1):

# Set the current index as the minimum

min_index = i

# Loop through the rest of the list to find the actual minimum

for j in range(i + 1, len(my_list)):

if my_list[j] < my_list[min_index]:

min_index = j

# Swap the values if the minimum is not already at position i

if i != min_index:

temp = my_list[i]

my_list[i] = my_list[min_index]

my_list[min_index] = temp

return my_list

Outer loop (i): Goes through the list from index 0 to len(list)-2.
- This loop represents the current position where we want to place the minimum element.
Set min_index:
- Initially, we assume the first unsorted element is the minimum.
Inner loop (j): Scans the rest of the list to find the true minimum.
- If a smaller value is found, min_index is updated.
Swap if necessary:
- Only swap if the minimum index found is different from i.
- This avoids unnecessary swaps when the current element is already the minimum.
Return sorted list.

Output:

After the first pass, the smallest element is in its correct position.
After the second pass, the second smallest element is in its correct position.
This continues until the entire list is sorted.
Time Complexity: O(n²) in all cases.
Space Complexity: O(1) (in-place sorting).