Python integer to letter grade issue

问题

I am attempting to troubleshoot the errors in this piece of code:

import time

while1 = True

def grader (z):
    if   z >= 0 or z <= 59:
        return "F"
    elif z >= 60 or z <= 62:
        return "D-"
    elif z >= 62 or z <= 66:
        return "D"
    elif z >= 67 or z <= 69:
        return "D+"
    elif z >= 70 or z <= 62:
        return "C-"
    elif z >= 73 or z <= 76:
        return "C"
    elif z >= 77 or z <= 79:
        return "C+"   
    elif z >= 80 or z <= 82:
        return "B-"
    elif z >= 83 or z <= 86:
        return "B"
    elif z >= 87 or z <= 89:
        return "B+"
    elif z >= 90 or z <= 92:
        return "A-"
    else:
        return "A"



while while1:
    z = int(input("I will tell you the grade of this number, enter from 1 - 100\n"))
    if z < 0 or z > 100:
        print "Between 1 and 100 PLEASE!\n"
        while1 = True
    print grader(z)
    print "New number now\n"
    time.sleep(100)
    while1 = True

The argument in this situation is the integer z. z's value is set by the user and then the function should swing in and determine what letter grade z is worth, no matter what though it always returns 'F.'

This is rather befuddling to me (I am a novice) and I could use some assistance.

回答1:

Your problem is this:

if   z >= 0 or z <= 59:

Use:

if 0 <= z <= 59:

This alleviates the problem you're having using or instead of and and is more readable.

But you should look at the bisect module:

>>> 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']

回答2:

Your ors in grader should be ands. Anything you input that is greater than 0 will pass the first conditional, and so will be an F.

回答3:

Based on @Jon Clements' (great) answer, but I think easier to undestand:

def grade(score, breakpoints, grades):
    for k, v in zip(breakpoints, grades):
        if score > k:
            return v
    return 'Error'

grade(score, breakpoints=(90, 80, 70, 60, 0), grades=('A','B','C','D','E','F'))

回答4:

if x>0 or x < 59 will cover everything over 0

you are confusing ors with ands

if x>0 and x < 59 is only the range from 0 to 59

but can be more succinct as 0 < x < 59

回答5:

This has long since been solved, but a few points remain:

no need to set while1 = True again and again.
0 is a valid input in your code, but the text says that valid grades start at 1.

A complete solution, combined with @Jon Clement's great answer, would be

import time
from bisect import bisect

def grader(score,
           breakpoints=[60, 62, 67, 70, 73, 77, 80, 83, 87, 90, 93],
           grades=['F', 'D-', 'D', 'D+', 'C-', 'C', 'C+', 'B-', 'B', 'B+', 'A-',
                   'A']):
        i = bisect(breakpoints, score)
        return grades[i]

while True:
    z = int(input("I will tell you the grade of this number, enter from 1 - 100\n"))
    if z < 0 or z > 100:
        print "Between 0 and 100 PLEASE!\n"
        continue
    print grader(z)
    time.sleep(100)
    print "New number now\n"

来源：https://stackoverflow.com/questions/16907363/python-integer-to-letter-grade-issue

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