Python: Insertion Sort algorithm

Insertion Sort algorithm explained in animated demo, with example Python 3 code implementation.

PYTHON SORTING ALGORITHMS

#Python

[hunterrees]

A quick tip for anyone: you don’t need a temp variable when swapping two variables. In python, you can write the following code:
x, y = y, x
This swaps both of the variables in one line because python allows recursive referencing of variables, and it allows multiple identifiers to be assigned in one line.

[shivamkumarrai]

2:57
correction required:: for j in range(i-1, -1, -1):

check for test case:: A=[10, 9, 8, 5, 3, 7, 92, 185, 78, 1, 0, 65]

[vanshgulati]

sir there is an error in the first code as in there 0th index will not be included hence first element would not be sorted it should be - for j in range(i-1, -1, -1) thanks sir for posting such videos and making people good learners you have helped me to gain interest and made me capable of finding bugs
xoxoxoxo :)

[soseofficial]

best teacher of sorting algorithms in python i found on youtube so far... Thank you Joe James.

[randyrichardson]

Thanks for all these videos, Joe. I've been programming in Python for about a year now, but none of the books I've read teach anything about algorithms or data structures. I finally feel like I'm learning REAL computer science. Cheers.

[sathyanarayanankulasekaran]

Thanks for the videos Sir, two corrections required in the code are, Arr[j]=currNum inside the if loop so that the currnum value is retained, second is for range is (i-1, -1, -1)

[hrithikrana]

this video is still usefull after 5 thank you sir, great explanation

[yourdadishere]

Yeah, really great job, man. I know this is a bit old but it's still a goodie. Having been an educator in a different area of study for many years, I honestly have to say that what charmed me the most was that you explained each line and what was happening in the algorithm by referring to what is left or right. So many other youtubers have forgotten to keep this compass rose available for listeners and simple rushed through the code.

[abhishekparida]

Thank you for the video.
I think the stop parameter of the second for-loop should be -1, not 0.

for j in range(i-1, -1, -1)

[drustan]

For those who are struggling to keep up with this video, this is the correct and working code for the nested loop version:
def insertion(lst):
for i in range(1, len(lst)):
print(i)
for j in range(i-1, -1, -1):
print(j)
if lst[j]>lst[j+1]:
lst[j], lst[j+1]=lst[j+1], lst[j]
print(lst)
else:
break
return lst


# "Optimized" insertion sort algo based on nesterd loops
def insertion(A):
for i in range(1, len(A)):
curNum=A[i]
for j in range(i-1, -1, -1):
if A[j] > curNum:
A[j+1] = A[j]
A[j]=curNum
else:
break
return A
#The code below will t

[AH-xbeb]

Thanks, I did the code and realized the first index was never sorted. Took me a while to solve the issue on my own, but later realized that the answer was down in the comment section lol.

[francisssemwanga]

Been trying this several times to sort in ascending order and below is code which worked for me, hope it helps someone else. By the way Joe thanks for the excellent videos.

def insertion_sort(A):
for i in range(1, len(A)+1):
for j in range(i-1, 0, -1 ):
if A[j] > A[j-1]:
break
else:
A[j-1], A[j] = A[j], A[j-1]
return A

[kerodfresenbetgebremedhin]

set 0 in the for loop parameter for the ending index to -1 and it should work fine

[shikhatripathi]

Mr.Joe u very beautifully explained the insertion sort 😊

[arpankumarlahiri]

consideration : The left of the current number is already sorted
You can use binary search method for comparision and then swap that will decrease time complexity
O(n^2) O(nlogn)

[yesme]

There are 2 problems in this python code with the 2 for loops.
for j in range(i - 1, 0, -1) is not valid. You are missing the first 2 numbers. It should be for j in range(i - 1, -1, -1)
The if min_value < a_list[j]: ... else also does not work if you have only 2 numbers to swap. If you have 2 numbers, the code never enters the else and the first value is not overwritten by the min_value

[shanmalik]

Another way of doing the same:

def InsertionSort(Sortee):
for index, item in enumerate(Sortee):
if index==0:
continue
ti=index
while item<Sortee[ti-1]:
Sortee[ti], Sortee[ti-1] = Sortee[ti-1], Sortee[ti]
ti=ti-1
if ti==0:
break

[harshulgoel]

thank you Joe James for these lovely tutorials you have helped me a lot in getting better at Python

[darshankokal]

Fast and simple to understand!
Thanks for making such wonderful content!! 😃

[virl]

At 2:27 it will be
for j in range(i-1, -1, -1):