Using functions for multiple inputs [Python]

Question

I'm new to python, taking my first class in it right now, only about 4 weeks in.

The assignment is to calculate test average and display the grade for each test inputted.

Part of the assignment is to use a function to calculate the average as well as deciding what letter grade to be assigned to each score.

As I understand it, functions are supposed to help cut down global variables.

My question is this: how do I condense this code?

I don't know how to use a function for deciding letter grade and then displaying that without creating a global variable for each grade that has been inputted.

If you notice any redundancy in my code, I would appreciate a heads up and a little lesson on how to cut that out. I can already smell the mark downs I will get if I turn this in as is...

 def main():
 grade1=float(input( "Enter score (0-100):"))
 while (grade1 <0 or grade1 >100 ):
 if grade1 <0 or grade1 >100:
 print("Please enter a valid grade")
 grade1=float(input( "Enter score (0-100):"))
 grade2=float(input( "Enter score (0-100):"))
 while (grade2 <0 or grade2 >100 ):
 if grade2 <0 or grade2 >100:
 print("Please enter a valid grade")
 grade2=float(input( "Enter score (0-100):"))
 grade3=float(input( "Enter score (0-100):"))
 while (grade3 <0 or grade3 >100 ):
 if grade3 <0 or grade3 >100:
 print("Please enter a valid grade")
 grade3=float(input( "Enter score (0-100):"))
 grade4=float(input( "Enter score (0-100):"))
 while (grade4 <0 or grade4 >100 ):
 if grade4 <0 or grade4 >100:
 print("Please enter a valid grade")
 grade4=float(input( "Enter score (0-100):"))
 grade5=float(input( "Enter score (0-100):"))
 while (grade5 <0 or grade5 >100 ):
 if grade5 <0 or grade5 >100:
 print("Please enter a valid grade")
 grade5=float(input( "Enter score (0-100):"))
 total=grade1+grade2+grade3+grade4+grade5
 testAverage=calcAverage(total)
 eachGrade1=determineGrade(grade1)
 eachGrade2=determineGrade(grade2)
 eachGrade3=determineGrade(grade3)
 eachGrade4=determineGrade(grade4)
 eachGrade5=determineGrade(grade5)
 print("\nTest #1 grade:", (eachGrade1))
 print("Test #2 grade:", (eachGrade2))
 print("Test #3 grade:", (eachGrade3))
 print("Test #4 grade:", (eachGrade4))
 print("Test #5 grade:", (eachGrade5))
 print("\nTest average:", (testAverage),("%"))
def calcAverage(total):
 average=total/5
 return average
def determineGrade(grade):
 if grade >=90:
 return "A"
 elif grade >=80:
 return "B"
 elif grade >=70:
 return "C"
 elif grade >=60:
 return "D"
 else:
 return "F"

• Kurt: Rule #1 of coding, NEVER copy and paste. Whenever you copy and paste that's really a function.
• Zachary McCauley: I'm afraid I don't follow, what are you referring to?
• TigerhawkT3: You might want to carefully review the course materials regarding this assignment. It probably discusses topics like functions, return values, and lists.
• Kurt: You have 5 identical code blocks with the only difference being the variable gradeX. Did you copy and paste that code and then change the variable name? I suspect you did. Instead of doing that, make a function. Granted that is sort of your question but nobody here is interested in doing your homework for you.
• Zachary McCauley: @kurt that is certainly not the intent of this post. Being only weeks into my first ever coding class, there are concepts that are elusive to me and that I feel I cannot devise from the book and simply am looking for help.

Answer 1

I won't refactor your whole code, but here's a few pointers:

First of all, you need a function to get the user input, let's call it get_score. I won't go into the details here because there's an excellent resource on how to write a function for that here: Asking the user for input until they give a valid response. That function should return a float or integer, so don't forget that input (assuming you are using Python 3) returns a string which you have to cast to int or float manually.

To get a list of n scores, I propose the function:

def get_n_scores(n):
 return [get_score() for _ in range(n)]

The stuff in the square brackets is a list comprehension and equivalent to:

scores = []
for _ in range(n):
 scores.append(get_score())

Use this code instead if you are not comfortable with the comprehension (don't forget to return result).

The variable name _ is commonly used to indicate a temporary value that is not used (other than for iteration).

You can avoid declaring grade1 ... grade5 by calling all_scores = get_n_scores(5), which will return a list with the user input. Remember that indexing is zero-based, so you'll be able to access all_scores[0] ... all_scores[4].

Instead of hardcoding total, you can just apply the built in sum function: total = sum(all_scores), assuming all_scores holds integers or floats.

Finally, you can determine the grade for each score by applying your function determineGrade to every score in all_scores. Again, you can use a comprehension:

all_grades = [determineGrade(score) for score in all_scores]

or the traditional:

all_grades = []
for score in all_scores:
 all_grades.append(determineGrade(score))

The other stuff looks okay, except that in order to print the grade you can just loop over all_grades and print the items. It's up to you if you want to write further functions that wrap a couple of the individual function calls we're making.

In general, always avoid repeating yourself, write a function instead.

• Zachary McCauley: Thank you for taking the time to write this all out. Going to re-do the entire thing while using your advice and trying to use functions more appropriately.
• Byte Commander: Don't forget that the average of all numbers in a list is average = sum(my_list) / len(my_list), you don't have to hard-code the length either.
• timgeb: @ByteCommander Indeed, calcaverage should take two arguments (if you want a function for that at all). I missed that.

Answer 2

I'll write is as below:

def get_grade():
 while(True):
 grade = float(input("Enter score (0-100):"))
 if grade >= 0 and grade <= 100:
 return grade
 print("Please enter a valid grade!")
def get_average(sum_val, counter):
 return sum_val/counter
def determine_grade(grade):
 if grade >=90:
 return "A"
 elif grade >=80:
 return "B"
 elif grade >=70:
 return "C"
 elif grade >=60:
 return "D"
 else:
 return "F"
test_num = 5
sum_val = 0
result = {}
for i in range(test_num):
 grade = get_grade()
 result[i] = determine_grade(grade)
 sum_val += grade
for key in result:
 print ("Test %d Grade is %s" % (key+1, result[key]))
avg = get_average(sum_val, test_num)
print ("Average is %d" % avg)

Works like this:

>>> ================================ RESTART ================================
>>> 
Enter score (0-100):89
Enter score (0-100):34
Enter score (0-100):348
Please enter a valid grade!
Enter score (0-100):34
Enter score (0-100):90
Enter score (0-100):85
Test 1 Grade is B
Test 2 Grade is F
Test 3 Grade is F
Test 4 Grade is A
Test 5 Grade is B
Average is 66
>>>

• Zachary McCauley: Thank you for taking the time to write. I believe you used a number of things I have yet to learn (I am very new). But I intend to take this and make a tertiary page of the same code using your methods to learn something.
• EbraHim: @ZacharyMcCauley You are welcome. Google for for loop in Python, dictionary in Python and formatted print in Python. That's all you need for this program. Wish you success.
• Byte Commander: The float conversion inside getAverage(...) is superfluous. Also Python naming conventions are snake case (i.e. your function and variable names should look like get_average instead). Additionally, you can omit the counter variable because when you use it, its value is determined to be equal to Test_num.
• EbraHim: @ByteCommander Thank you dear friend. I updated my answer based on your tips.
• Byte Commander: You did not replace counter with Test_num : get_average(sum_val, counter)