Finding the Maximum and Minimum value in python using loops

Question

I have an assignment where I let the user input as many scores and then I have to calculate the minimum and maximum value along with how many people got those scores using for-loop. I've calculated the average and the standard deviation:

elif user_option == 3:

    total = 0
    for val in scores_list:
        total = total + val
    average = total/ len(scores_list)
    print (average)
elif user_option == 2:
    total = 0
    for val in scores_list:
        total = total + val
    average = total/ len(scores_list)
    diffsquared = 0
    sum_diffsquared = 0
    for val in scores_list:
        diffsquared= (val - average)**2
        sum_diffsquared= diffsquared + sum_diffsquared
    stdev= sqrt((sum_diffsquared)/len(scores_list))
    print(stdev)

Any ideas how to find the min and max values?

Some reformatting is in order :/. Also give a short, standalone and runnable sample. — Veedrac
– Veedrac, Commented Sep 29, 2013 at 21:31
Is there a first part to your if statement? Because you can't start with elif... — SethMMorton
– SethMMorton, Commented Sep 29, 2013 at 21:40

Shashank · Accepted Answer · 2013-09-29 21:50:10Z

1

Something like this?

min_val = float("inf")
max_val = -float("inf")
count_min = 0
count_max = 0

for val in scores_list:
    if val < min_val:
        min_val = val
        count_min = 1
    elif val == min_val:
        count_min += 1

    if val > max_val:
        max_val = val
        count_max = 1
    elif val == max_val:
        count_max += 1

print "Minimum score:", min_val
print "Maximum score:", max_val
print "Number of students with minimum score:", count_min
print "Number of students with maximum score:", count_max

EDIT: As @GL770 has noted in the comments, sys.maxint is only available in Python 2.x. In Python 2.x you could have done something like this.:

import sys
min_val = sys.maxint
max_val = -sys.maxint - 1

The float("inf") thing also works in Python 2.x though so this method is not required.

edited Sep 29, 2013 at 21:50

answered Sep 29, 2013 at 21:32

Shashank

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4 Comments

Shashank Over a year ago

@GL770 Thanks for letting me know. I made it float("inf") and -float("inf") instead. That should be Python 3 compatible.

bcollins Over a year ago

I don't think your count_min, count_max values are correct. Think about: scores = [6,6,6,7,7,7,8,8,9,3,3,3,2,2,2,1,1]

Shashank Over a year ago

@bcollins yeah theres a reason because in your code the count_min never gets reset to 1 if it finds a new minimum value. Also try running my code with that list. It works. For me it printed: Minimum score: 1 Maximum score: 9 Number of students with minimum score: 3 Number of students with maximum score: 1

Shashank Over a year ago

Well in your edited list it prints: Minimum score: 1 Maximum score: 9 Number of students with minimum score: 2 Number of students with maximum score: 1 which is correct. I don't believe there are any issues with my code in terms of correctness.

bcollins · Accepted Answer · 2013-09-29 21:47:37Z

0

How about the built-in functions min() and max():

scores_min = min(scores_list)
scores_max = max(scores_list)

also don't forget about numpy:

import numpy
scores_array = numpy.array(scores_list)
scores_mean = numpy.mean(scores_array)
scores_std = numpy.std(scores_array)
scores_min = numpy.min(scores_array)
scores_max = numpy.max(scores_array)

edited Sep 29, 2013 at 21:47

answered Sep 29, 2013 at 21:33

bcollins

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3 Comments

user300 Over a year ago

I can't use the built in functions. I have to use loops

Shashank Over a year ago

I'm fairly certain he's not allowed to use built-ins or numpy.

bcollins Over a year ago

ahh ok sorry. This is just an academic exercise.

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