Question

I am stuck with this coding problem from edx coding python 4.4.6:

#This is a long one -- our answer is 20 lines of code, but
#yours will probably be longer. That's because it's one of the
#more authentic problems we've done so far. This is a real
#problem you'll start to face if you want to start creating
#useful programs.
#
#One of the reasons that filetypes work is that everyone
#agrees how they are structured. A ".png" file, for example,
#always contains "PNG" in the first four characters to
#assure the program that the file is actually a png. If these
#standards were not set, it would be hard to write programs
#that know how to open and read the file.
#
#Let’s define a new filetype called ".cs1301".
#In this file, every line should be structured like so:
#
#number assignment_name grade total weight
#
#In this file, each component will meet the following
#description:
#
# - number: an integer-like value of the assignment number
#
# - assignment_name: a string value of the assignment name
#
# - grade: an integer-like value of a student’s grade
#
# - total: an integer-like value of the total possible
# number of points
#
# - weight: a float-like value ranging from 0 to 1
# representing the percent of the student’s grade this
# assignment is worth. All the weights should add up to 1.
#
#Each component should be separated with exactly one space.
#A good sample file is available to view as
#"sample.cs1301".
#
#Write a function called format_checker that accepts a
#filename and returns True if the file contents accurately
#conform to the described format. Otherwise the function
#should return False. In other words, it should return True
#if:
#
# - Each line has five elements separated by spaces, AND
# - The first, third, and fourth elements are integers, AND
# - The fifth element is a decimal number, AND
# - All the fifth elements add to 1.
#
#You can make changes to test.cs1301 to test your function,
#or test it with sample.cs1301. Right now, running it on
#sample.cs1301 should return True, and on test.cs1301
#should return False.
#
#Hint 1: .split() will likely help separate each line into
#its components.
#Hint 2: .split() returns a list. So, if you were to do
#something like say split_line = line.split(), then
#split_line[0] would give the first item, split_line[1] would
#give the second item, etc.
#Hint 3: If you're having trouble, try breaking it down by
#parts. First check the file to see if it has the right
#number of items per line, then whether the items are of
#the correct type, then whether the fifth elements add to
#1. Remember, you know how to do each individual check
#(checking types, adding numbers, finding list lengths) --
#the hard part is knitting this all together into one bigger
#solution.

#Write your function here!

#Test your function below. With the original values of these
#files, these should print True, then False:
print(format_checker("sample_1.cs1301"))
print(format_checker("sample_2.cs1301"))

Answer 1

Note: The required code for the function format_checker() is highlighted in grey and bold.

#This is a long one -- our answer is 20 lines of code,

#but yours will probably be longer. That's because it's

#one of the more authentic problems we've done so far.

#This is a real problem you'll start to face if you want

#to start creating useful programs.

#

#One of the reasons that filetypes work is that everyone

#agrees how they are structured. A ".png" file, for

#example, always contains "PNG" in the first four

#characters to assure the program that the file is

#actually a png. If these standards were not set, it

#would be hard to write programs that know how to open

#and read the file.

#

#Let’s define a new filetype called ".cs1301".

#In this file, every line should be structured like so:

#

#number assignment_name grade total weight

#

#In this file, each component will meet the following

#description:

#

# - number: an integer-like value of the assignment

#   number

#

# - assignment_name: a string value of the assignment

#   name

#

# - grade: an integer-like value of a student’s grade

#

# - total: an integer-like value of the total possible

#   number of points

#

# - weight: a float-like value ranging from 0 to 1

# representing the percent of the student’s grade this

# assignment is worth. All the weights should add up to 1.

#

#Each component should be separated with exactly one

#space.

#A good sample file is available to view as

#"sample.cs1301".

#

#Write a function called format_checker that accepts a

#filename and returns True if the file contents

#accurately confirm to the described format. Otherwise

#the function should return False. In other words, it

#should return True if:

#

# - Each line has five elements separated by spaces, AND

# - The first, third, and fourth elements are integers,

#   AND

# - The fifth element is a decimal number, AND

# - All the fifth elements add to 1.

#

#You can make changes to test.cs1301 to test your

#function, or test it with sample.cs1301. Right now,

#running it on sample.cs1301 should return True, and on

#test.cs1301 should return False.

#

#Hint 1: .split() will likely help separate each line

#into its components.

#Hint 2: .split() returns a list. So, if you were to do

#something like say split_line = line.split(), then

#split_line[0] would give the first item, split_line[1]

#would give the second item, etc.

#Hint 3: If you're having trouble, try breaking it down

#by parts. First check the file to see if it has the

#right number of items per line, then whether the items

#are of the correct type, then whether the fifth elements

#add to 1. Remember, you know how to do each individual

#check (checking types, adding numbers, finding list

#lengths) -- the hard part is knitting this all together

#into one bigger solution.

#Screenshot of the code:

#Sample Input File (sample_1.cs1301):

#Sample Input File (sample_2.cs1301):

#Sample Output:

#Code to copy:

#Write your function here!

#Define the function format_checker() having a file name

#as function parameter.

def format_checker(filename):

    #Open the file in read mode.

    infile = open(filename, 'r')

    #Read all lines of the file.

    fileLines = infile.readlines()

   

    #Close the file.

    infile.close()

    #Declare and initialize required variable to store

    #the total of weights.

    totalWeight = 0

    #Start a while loop over the lines read from the

    #file.

    for currentLine in fileLines:

       

        #Split the current line through spaces.

        split_line = currentLine.split(' ')

        #If the length of the splitted line or list of

        #items of the current line is not 5, then return

        #false.

        if(len(split_line) != 5):

            return False

       

        #Start a try/except block.

        try:

            #Chnage the type of item at 0, 2, 3 index to

            #integer from string and the type of item at

            #4th index will be chnaged to float from

            #string.

            split_line[0] = int(split_line[0])

            split_line[2] = int(split_line[2])

            split_line[3] = int(split_line[3])

            split_line[4] = float(split_line[4])

          

            #If the item at 4th index i.e. weight is not

            #in the range 0 and 1, then return false.

            if(split_line[4] < 0 or split_line[4] > 1):

                return False

       

        #Start the except block and return false, if

        #there is any type mismatch.

        except:

            return False

       

        #Add the item at 4th index i.e. weight to the

        #totalWeight.

        totalWeight = totalWeight + split_line[4]

   

    #If the value of the totalWeight is not equal to 1,

    #then return false.

    if(totalWeight != 1):

        return False

    #Otherwisem return true.   

    return True

#Test your function below. With the original values of

#these files, these should print True, then False:

print(format_checker("sample_1.cs1301"))

print(format_checker("sample_2.cs1301"))

Sample Input File (sample_1.cs1301):

1 assignment_1 85 100 0.05

2 assignment_2 80 100 0.05

3 assignment_3 95 100 0.05

4 assignment_4 95 100 0.05

5 assignment_5 80 100 0.05

6 exam_1 85 86 0.1

7 assignment_6 100 100 0.05

8 assignment_7 97 100 0.05

9 exam_2 89 100 0.1

10 assignment_8 93 100 0.05

11 assignment_9 99 100 0.05

12 exam_3 92 100 0.1

13 final_exam 95 100 0.25

Sample Input File (sample_2.cs1301):

Hey kid!

Did you know that dragons love tacos?