python - How can I simplify repetitive if-elif statements in my grading system function?

Question

The goal is to build a program to convert scores from a '0 to 1' system to an 'F to A' system:

• If score >= 0.9 would print 'A'
• If score >= 0.8 would print 'B'
• 0.7, C
• 0.6, D
• And any value below that point, print F

This is the way to build it and it works on the program, but it's somewhat repetitive:

if scr >= 0.9:
    print('A')
elif scr >= 0.8:
    print('B')
elif scr >= 0.7:
    print('C')
elif scr >= 0.6:
    print('D')
else:
    print('F')

I would like to know if there is a way to build a function so that the compound statements wouldn't be as repetitive.

I'm a total beginner, but would something in the lines of :

def convertgrade(scr, numgrd, ltrgrd):
    if scr >= numgrd:
        return ltrgrd
    if scr < numgrd:
        return ltrgrd

be possible?

The intention here is that later we can call it by only passing the scr, numbergrade and letter grade as arguments:

convertgrade(scr, 0.9, 'A')
convertgrade(scr, 0.8, 'B')
convertgrade(scr, 0.7, 'C')
convertgrade(scr, 0.6, 'D')
convertgrade(scr, 0.6, 'F')

If it would be possible to pass fewer arguments, it would be even better.

Answer 1

You can use the bisect module to do a numeric table lookup:

from bisect import bisect 

def grade(score, breakpoints=[60, 70, 80, 90], grades='FDCBA'):
     i = bisect(breakpoints, score)
     return grades[i]

>>> [grade(score) for score in [33, 99, 77, 70, 89, 90, 100]]
['F', 'A', 'C', 'C', 'B', 'A', 'A']