Chapter 11, Problem 3PE

Program Plan Intro

Modified gpasort program

Program plan:

• Import the necessary modules in “grade_sort.py” file.
• Define the “make_Student()” function,
  • Returns student record values to the caller.
• Define the “read_Students()” function,
  • Returns the list of student record to the caller.
• Define the “write_Students()” function,
  • Write the student record.
• Define the “main()” function,
  • Get the input file.
  • Read the students record for the input file.
  • Make a “while” loop for “True”.
    • Get the type of input to sort.
    • Get the type of ordering from the user.
      • Check whether the type is “GPA” using “if”.
        • If it is true, sort the data based on the “GPA”.
        • Rename the file name.
        • Check whether the ordering is "D"
        • • If it is true, reverse the data.
        • Use “break” to exit.
      • Check whether the type is “name” using “elif”.
        • If it is true, sort the data based on the “name”.
        • Rename the file name.
        • Check whether the ordering is "D"
        • • If it is true, reverse the data.
        • Use “break” to exit.
      • Check whether the type is “credits” using “if”.
        • If it is true, sort the data based on the “credits”.
        • Rename the file name.
        • Check whether the ordering is "D"
        • • If it is true, reverse the data.
        • Use “break” to exit.
        • • • Write the data into the output file.
• Create a class Student in “gpa.py” file,
  • Define the “_init_()” method.
    • Assign name hours and GPoints.
      • • • • Define the “get_Name()” method.
              • Return the name.
            • Define the “get_Hours()” method.
              • Return hours.
            • Define the “getQ_Points()” method.
              • Return GPoints.
            • Define the “gpa()” method.
              • Return gpa
            • Define the “make_Student()” method.
              • Return name, hours, and grade points.
            • Define the “main()” function.
• Call the “main()” function.

Explanation of Solution

Program:

File name: “gpasort.py”

#Import required module

from gpa import Student

#Define the function make_Student()

def make_Student(info_Str):

    #Make multiple assignment

    Name, Hours, Gpoints = info_Str.split("\t")

    #Return constructor

    return Student(Name, Hours, Gpoints)

#Define the function read_Students()

def read_Students(file_name):

    #Open the input file for reading

    in_file = open(file_name, 'r')

    #Create an empty list

    Students = []

    #Create for loop to iterate over all lines in a file

    for line in in_file:

        #Append the line in a list

        Students.append(make_Student(line))

    #Close the input file

    in_file.close()

    #Return the list

    return Students

#Define the function write_Students()

def write_Students(Students, file_name):

    #Open output file to write

    out_file = open(file_name, 'w')

    #Create a for loop to iterate over list

    for s in Students:

        #Print output

        print("{0}\t{1}\t{2}".format(s.get_Name(), s.get_Hours(), s.getQ_Points()), file = out_file)

    #Close the output file

    out_file.close()

#Define the main() function

def main():

    #Print the string

    print("This program sorts student grade information by GPA, name, or credits.")

    #Get the input file

    file_name = 'gpa1.txt'

    #Assign the data return from read_Students()

    data = read_Students(file_name)

    #Create "while" loop

    while True:

        #Get the type

        x = (input('Type "GPA", "name", or "credits" >>>  '))

        #Get the type of ordering

        m = (input('Type "A" for ascending, "D" for descending.'))

        #Check whether the type is "GPA"

        if x == 'GPA':

            #Sort the data based on the gpa

            data.sort(key=Student.gpa)

            #Rename the file name

            s = "_(GPA)"

            #Check whether the ordering is "D"

            if m == "D":

                #Reverse the data

                data.reverse()

            #Use break to exit

            break

        #Check whether the type is "name"

        elif x == 'name':

            #Sort the data based on the name

            data.sort(key=Student.get_Name)

            #Rename the file name

            s = "_(name)"

            #Check whether the ordering is "D"

            if m == "D":

                #Reverse the data

                data.reverse()

            #Use break to exit

            break

        #Check whether the type is "credits"

        elif x == 'credits':

            #Sort the data based on the credits

            data.sort(key=Student.getQ_Points)

            #Rename the file name

            s = "_(credits)"

            #Check whether the ordering is "D"

            if m == "D":

                #Reverse the data

                data.reverse()

            #Use break to exit

            break

        #Otherwise

        else:

            #Print the string

            print("Please try again.")

    #Assign the output file

    filename = "GPA2" + s + ".py"

    #Write the data into output file

    write_Students(data, filename)

    #Print output file

    print("The data has been written to", filename)

#Call the main function

if __name__ == '__main__': main()

File name: “gpa.py”

#Create a class Student

class Student:

    #Define _init_() method

    def __init__(self, Name, Hours, Gpoints):

        self.Name = Name

        self.Hours = float(Hours)

        self.Gpoints = float(Gpoints)

    #Define get_Name() method

    def get_Name(self):

        #Return the name

        return self.Name

    #Define get_Hours()

    def get_Hours(self):

        #return hours

        return self.Hours

    #Define getQ_Points()

    def getQ_Points(self):

        #return grade points

        return self.Gpoints

    #Define the funcition gpa()

    def gpa(self):

        #return the value

        return self.Gpoints / self.Hours

#Define the function make_Student()

def make_Student(info_Str):

    #Make multiple assignment

    Name, Hours, Gpoints = info_Str.split("\t")

   #Return the constructor

    return Student(Name, Hours, Gpoints)

#Define the main() function

def main():

    #Open the input file for reading

    file_name = input("Enter the name of the grade file: ")

    in_file = open(file_name, 'r')

    #Set best to the record for the first student in the file

    best = make_Student(in_file.readline())

    #Process lines of the file using "for" loop

    for line in in_file:

        #Make the line of file into a student record

        s = make_Student(line)

        #Checck whether the student is best so far

        if s.gpa() > best.gpa():

            #Assign the best student record

            best = s

    #Close the input file

    in_file.close()

    #Print information about the best student

    print("The best student is:", best.get_Name())

    print("Hours:", best.get_Hours())

    print("GPA:", best.gpa())

if __name__ == '__main__':

    #Call the main() function

    main()

Sample Output

Contents of “gpa1.txt”

Adams, Henry    127    228

Computewell, Susan    100    400

DibbleBit, Denny    18    41.5

Jones, Jim    48.5    155

Smith, Frank    37    125.33

Screenshot of output file “GPA2.py” before execution:

Output:

This program sorts student grade information by GPA, name, or credits.

Type "GPA", "name", or "credits" >>>  name

Type "A" for ascending, "D" for descending.D

The data has been written to GPA2_(name).py

>>>

Screenshot of output file “GPA2_(name).py after execution:

Additional output:

This program sorts student grade information by GPA, name, or credits.

Type "GPA", "name", or "credits" >>>  GPA

Type "A" for ascending, "D" for descending.D

The data has been written to GPA2_(GPA).py

>>>

Screenshot of output file “GPA2_(gpa).py after execution: