Defining Class Methods in Python 3.43 [closed] - python-3.x

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I'm trying to define a class called Student with a name, ID number, test scores, and average of test scores. When I run the program, everything works except printing the test score average after new scores have been appended to the original score list in the class. It keeps the original average of "Undefined", and I can't figure out why it's not updating.
class Student:
"""The Student class stores the first and last name of a student,
as well as all of their exam scores and overall average."""
def __init__(self, Id, first='', last=''):
"""Create a student object (e.g., Student(123654, Jane, Doe))"""
self.Id = Id
self.first_name = first
self.last_name = last
self.scores = []
self.average = 'Undefined'
def getId(self):
"""Retrieves student's Id number"""
return self.Id
def getfirst(self):
"""Retrieves student's first name"""
return self.first_name
def getlast(self):
"""Retrieves student's last name"""
return self.last_name
def getscore(self):
"""Retrieves list of student's test scores"""
return self.scores
def getaverage(self):
"""Retrieves student's average test score"""
return self.average
def add_score(self, score):
"""Updates student's list of test scores"""
self.scores.append(score)
return self.scores
def calculate_average(self):
"""Updates student's average test score using updated list of scores"""
self.average = sum(self.scores) / len(self.scores)
return self.average
def __str__(self):
"""Organizes student's information into a printable statement"""
return "ID: " + self.Id + " Name: " + self.first_name + " " + \
self.last_name + " Average Score: " + self.average
def main():
print('This program reads student data from a file, prompts the')
print('user for the total number of exams completed, and outputs ')
print('the average score for each student.')
infile = open("student_data.txt", "r")
student_list = []
num_exams = int (input('Enter the number of exams completed: '))
for line in infile:
Id, first, last = line.split()
student = Student(Id, first, last)
print('Enter scores for student', Id)
for i in range(num_exams):
score = int (input('Enter an exam score: '))
student.add_score(score)
student_list.append(student)
infile.close()
for student in student_list:
student.getscore
student.calculate_average
student.getaverage
print(student)
main()

Answer 1

Here is a more Pythonic class definition:
from math import nan
from statistics import mean, StatisticsError
class Student(object):
"""The Student class stores the first and last name of a student,
as well as all of their exam scores and overall average."""
def __init__(self, Id, first='', last=''):
"""Create a student object (e.g., Student(123654, Jane, Doe))"""
self.Id = Id
self.first = first
self.last = last
self.scores = []
def __repr__(self):
"""Organizes student's information into a printable statement"""
return "{0.__class__.__name__}({0.Id}, '{0.first}', '{0.last}', {0.average})".format(self)
def __str__(self):
"""Organizes student's information into a printable statement"""
return "{0.__class__.__name__}({0.Id}, '{0.first}', '{0.last}', {0.average})".format(self)
#property
def average(self):
try:
return mean(self.scores)
except StatisticsError:
return nan
def add_score(self, score):
"""Updates student's list of test scores"""
self.scores.append(score)
By using the #property decorator, self.average is a property which will calculate itself. This helps avoid the question of "has self.average been updated yet?", since all of the calculation is done by the attribute itself. Also, this way you can use nan (not-a-number) if there are no scores.

Answer 2

One thing that strikes me as something that needs to be addressed is that you are not calling the class methods in the final loop.
try
for student in student_list:
student.calculate_average()
print(student)
The rest of the methods are unnecessary as (I assume) you only want to print the values, and not store it in variables.