# Copyright 2014 Brett Slatkin, Pearson Education Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Preamble to mimick book environment
import logging
from pprint import pprint
from sys import stdout as STDOUT
# Example 1
class SimpleGradebook(object):
def __init__(self):
self._grades = {}
def add_student(self, name):
self._grades[name] = []
def report_grade(self, name, score):
self._grades[name].append(score)
def average_grade(self, name):
grades = self._grades[name]
return sum(grades) / len(grades)
# Example 2
book = SimpleGradebook()
book.add_student('Isaac Newton')
book.report_grade('Isaac Newton', 90)
book.report_grade('Isaac Newton', 95)
book.report_grade('Isaac Newton', 85)
print(book.average_grade('Isaac Newton'))
90.0
# Example 3
class BySubjectGradebook(object):
def __init__(self):
self._grades = {}
def add_student(self, name):
self._grades[name] = {}
# Example 4
def report_grade(self, name, subject, grade):
by_subject = self._grades[name]
grade_list = by_subject.setdefault(subject, [])
grade_list.append(grade)
def average_grade(self, name):
by_subject = self._grades[name]
total, count = 0, 0
for grades in by_subject.values():
total += sum(grades)
count += len(grades)
return total / count
# Example 5
book = BySubjectGradebook()
book.add_student('Albert Einstein')
book.report_grade('Albert Einstein', 'Math', 75)
book.report_grade('Albert Einstein', 'Math', 65)
book.report_grade('Albert Einstein', 'Gym', 90)
book.report_grade('Albert Einstein', 'Gym', 95)
print(book.average_grade('Albert Einstein'))
81.25
# Example 6
class WeightedGradebook(object):
def __init__(self):
self._grades = {}
def add_student(self, name):
self._grades[name] = {}
def report_grade(self, name, subject, score, weight):
by_subject = self._grades[name]
grade_list = by_subject.setdefault(subject, [])
grade_list.append((score, weight))
# Example 7
def average_grade(self, name):
by_subject = self._grades[name]
score_sum, score_count = 0, 0
for subject, scores in by_subject.items():
subject_avg, total_weight = 0, 0
for score, weight in scores:
subject_avg += score * weight
total_weight += weight
score_sum += subject_avg / total_weight
score_count += 1
return score_sum / score_count
# Example 8
book = WeightedGradebook()
book.add_student('Albert Einstein')
book.report_grade('Albert Einstein', 'Math', 80, 0.10)
book.report_grade('Albert Einstein', 'Math', 80, 0.10)
book.report_grade('Albert Einstein', 'Math', 70, 0.80)
book.report_grade('Albert Einstein', 'Gym', 100, 0.40)
book.report_grade('Albert Einstein', 'Gym', 85, 0.60)
print(book.average_grade('Albert Einstein'))
81.5
# Example 9
grades = []
grades.append((95, 0.45))
grades.append((85, 0.55))
total = sum(score * weight for score, weight in grades)
total_weight = sum(weight for _, weight in grades)
average_grade = total / total_weight
print(average_grade)
89.5
# Example 10
grades = []
grades.append((95, 0.45, 'Great job'))
grades.append((85, 0.55, 'Better next time'))
total = sum(score * weight for score, weight, _ in grades)
total_weight = sum(weight for _, weight, _ in grades)
average_grade = total / total_weight
print(average_grade)
89.5
# Example 11
import collections
Grade = collections.namedtuple('Grade', ('score', 'weight'))
# Example 12
class Subject(object):
def __init__(self):
self._grades = []
def report_grade(self, score, weight):
self._grades.append(Grade(score, weight))
def average_grade(self):
total, total_weight = 0, 0
for grade in self._grades:
total += grade.score * grade.weight
total_weight += grade.weight
return total / total_weight
# Example 13
class Student(object):
def __init__(self):
self._subjects = {}
def subject(self, name):
if name not in self._subjects:
self._subjects[name] = Subject()
return self._subjects[name]
def average_grade(self):
total, count = 0, 0
for subject in self._subjects.values():
total += subject.average_grade()
count += 1
return total / count
# Example 14
class Gradebook(object):
def __init__(self):
self._students = {}
def student(self, name):
if name not in self._students:
self._students[name] = Student()
return self._students[name]
# Example 15
book = Gradebook()
albert = book.student('Albert Einstein')
math = albert.subject('Math')
math.report_grade(80, 0.10)
math.report_grade(80, 0.10)
math.report_grade(70, 0.80)
gym = albert.subject('Gym')
gym.report_grade(100, 0.40)
gym.report_grade(85, 0.60)
print(albert.average_grade())
81.5