Find the Percentage from HackerRank

Question

I am learning python by solving python module from HackerRank. This problem is Find the Percentage.

You have a record of N students. Each record contains the student's name, and their percent marks in Maths, Physics and Chemistry. The marks can be floating values. The user enters some N integer followed by the names and marks for N students. You are required to save the record in a dictionary data type. The user then enters a student's name. Output the average percentage marks obtained by that student, correct to two decimal places.

Sample Input 0

3
Krishna 67 68 69 
Arjun 70 98 63 
Malika 52 56 60 
Malika

Sample Output 0

56.00

I need to improve this code by using better functions available in python.

def percentage(name):
    """
    Find percentage of marks of the student
    """

    marks = student_marks[name]
    total_marks = 0
    for mark in marks:
        total_marks += mark

    return format(total_marks/len(marks), '.2f')


if __name__ == '__main__':
    n = int(input())
    student_marks = {}
    for _ in range(n):
        name, *line = input().split()
        scores = list(map(float, line))
        student_marks[name] = scores
    query_name = input()
    print(percentage(query_name))

Answer 1

For a beginner this is some good code. I would make some additional adjustments.

• One-line docstrings should be on one line, not over 3. And should end with a period.
• You should only pass the marks to percentage and not rely on a global student_marks.
• You can use sum to compute total_marks.
• I'm not a fan of having format in the percentage function.
• You should move all the main code into a main function, if __name__ == '__main__': should really only call this.
• It's more idiomatic to use comprehensions than map, even more so when you have list(map(...)).
• It's pretty rude to call a student a query. You can just use name.

def percentage(marks):
    """Find percentage of marks of the student."""
    return sum(marks) / len(marks)


def main():
    """Main code."""
    n = int(input())
    student_marks = {}
    for _ in range(n):
        name, *scores = input().split()
        student_marks[name] = [float(score) for score in scores]
    name = input()
    result = percentage(student_marks[name])
    print(format(result, '.2f'))


if __name__ == '__main__':
    main()

• You can use statistics.mean rather than a custom made percentage.

• You can change the for loop into two comprehensions, a generator and dictionary comprehension.

  Note: I don't think comprehensions are better here, but are an 'as good' alternate.

import statistics


def main():
    """Main code."""
    _marks = (input().split() for _ in range(int(input())))
    student_marks = {
        name: [float(score) for score in scores]
        for name, *scores in _marks
    }
    result = statistics.mean(student_marks[input()])
    print(format(result, '.2f'))


if __name__ == '__main__':
    main()