Convert numbers to grades in python list

Question

I have a list which has the number of marks students have.

s = [50,62,15,76,57,97,82,99,45,23]

I want to grade students according to marks:

<40 - Fail
>50 - A Grade
>75 - A++ Grade

I can do this with iterating loops or I can find every list using lambda. for example :

>>> filter(lambda x:x>=50, s)
[50, 62, 76, 57, 97, 82, 99]

But, in the filter, I can work with only one function at a time (for example : marks greater than 50). Is there way where I can use filter and lambda and get required result in one line? Expecting the output as marks with grade. (ex : 50 - A, 62 - A, 76 - A++ ...)

Answer 1

Define a function that takes a mark and returns a human readable representation, you can use larsmans's expression or this one:

def grade(i):
    if i<40: return "Fail"
    if i>75: return "A++"
    if i>50: return "A"

Use string.format to format each entry and map to iterate over all of them:

li = map(lambda x: "{0} - {1}".format(x, grade(x)), s)

The resulting list now contains strings in the desired format.

for i in li: print i

# output

50 - None
62 - A
15 - Fail
76 - A++
57 - A
97 - A++
82 - A++
99 - A++
45 - None
23 - Fail