How to sort students list according to their Marks using Insertion sort in Python

Question

I am trying to sort students list and rank each student according to their marks using insertion sort. Data of students include Name, Roll no, Address, Mark.

Here, I store the Mark of students in one list - Marklist and other data of students in a second list - stdData.

I sorted the student Mark List using Insertion sort. But right now I have 2 separate lists. How can I merge and print the sorted list of each student with their marks?

import csv
stdData = []  # store RollNum,student name last name,address
Marklist = []  # store the final mark of each student
#generallist=[]
with open("studentlist.csv", "r") as f1:
    recordReader = csv.DictReader(f1)
    for row in recordReader:
        #generallist.append(row)
        row['Mark']=int(row['Mark'])
        Marklist.append(row['Mark'])
        stdData.append(row['RollNo'])
        stdData.append(row['Name'])
        stdData.append(row['LastName'])
        stdData.append(row['Address'])
print(Marklist)
print(stdData)
for i in range(1, len(Marklist)):
    key = Marklist[i]
    j = i - 1
    while j >= 0 and key < Marklist[j]:
        Marklist[j + 1] = Marklist[j]
        j -= 1
    Marklist[j + 1] = key

   print("Sorted List: ",Marklist)

Thanks.

Answer 1

You are very near to the correct solution. The answer lies in

• Storing student details as list of list. Eg: [ [student1 details], [student2 details], [student3 details] ]
• sorting stdData using the indices of MarkList.

Below is the code modified to address the above points:

import csv
stdData = []  # store RollNum,student name last name,address
Marklist = []  # store the final mark of each student
generallist=[]
with open("studentlist.csv", "r") as f1:
    recordReader = csv.DictReader(f1)
    for row in recordReader:
        #generallist.append(row)
        row['Mark']=int(row['Mark'])
        Marklist.append(row['Mark'])
        tmp_data = []
        tmp_data.append(row['RollNo'])
        tmp_data.append(row['Name'])
        tmp_data.append(row['LastName'])
        tmp_data.append(row['Address'])
        stdData.append(tmp_data) # Storing student details as list of lists
print(Marklist)
print(stdData)
for i in range(1, len(Marklist)):
    key = Marklist[i]
    data = stdData[i] # Sort the elements in stdData using indices of MarkList
    j = i - 1
    while j >= 0 and key < Marklist[j]:
        Marklist[j + 1] = Marklist[j]
        stdData[j+1] = stdData[j]
        j -= 1
    Marklist[j + 1] = key
    stdData[j+1] = data
print("Sorted List: ",Marklist)
for student_data in stdData:
    print(student_data)

Even though the above solution gives the correct answer, it uses two lists.

We can sort a list using keys (need not to be actual list elements). The below code implements it and is a better solution.

import csv
stdData = []  # store RollNum,student name last name,address

with open("studentlist.csv", "r") as f1:
    recordReader = csv.DictReader(f1)
    for row in recordReader:
        tmp_data = []
        tmp_data.append(row['RollNo'])
        tmp_data.append(row['Name'])
        tmp_data.append(int(row['Mark']))
        tmp_data.append(row['LastName'])
        tmp_data.append(row['Address'])
        stdData.append(tmp_data) # Storing student details as list of lists

print(stdData)
for i in range(1, len(stdData)):
    key = stdData[i][2] # here the key is the mark
    data = stdData[i] # we will copy the data to correct index
    j = i - 1
    while j >= 0 and key < stdData[j][2]:
        stdData[j+1] = stdData[j]
        j -= 1
    stdData[j+1] = data

print("Sorted List:")
for rollno, name, mark, lastname, address in stdData:
    print(rollno, name, mark, lastname, address)

Happy coding.