how to compare between index in lists without using the max methods-CodePudding

i solved this question but not in the acceptable way,how to improve the code?

the question is to create list function of grades and i will get the highest grade, we need to compare between the index

def grade(list1,list2,list):

highest=[]

newlist1= []
newlist1.append(list1[0])
newlist1.append(list2[0])
newlist1.append(list3[0])

max1=0
for i in newlist1:
    if i > max1:
        max1= i



newlist2= []
newlist2.append(list1[1])
newlist2.append(list2[1])
newlist2.append(list3[1])

max2=0
for i in newlist2:
    if i > max2:
        max2= i


newlist3= []
newlist3.append(list1[2])
newlist3.append(list2[2])
newlist3.append(list3[2])

max3=0
for i in newlist3:
    if i > max3:
     max3= i



newlist4= []
newlist4.append(list1[3])
newlist4.append(list2[3])
newlist4.append(list3[3])

max4=0
for i in newlist4:
    if i > max4:
       max4= i


newlist5= []
newlist5.append(list1[4])
newlist5.append(list2[4])
newlist5.append(list3[4])

max5=0
for i in newlist5:
    if i > max5:
       max5= i



highest.append(max1)
highest.append(max2)
highest.append(max3)
highest.append(max4)
highest.append(max5)




return(highest)

print(grade([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85]))

The answer is :[99, 100, 77, 96, 87]

CodePudding user response：

In a two-dimensional array of numpy, using transpose() is a simple way to get values. And using max() is a simple way to get highest value.

import numpy as np

def grade(list1, list2, list3):
    total_list = [list1, list2, list3]
    newlist = np.array(total_list).transpose()
    
    highest = []
    for data in newlist:
        highest.append(max(data))

    return highest

if __name__ == "__main__":
    print(grade([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85]))

CodePudding user response：

I you can't use max, define your own function, then simply loop over the zipped lists:

def get_max(elems):
    MAX = float('-inf')
    for e in elems:
        if e>MAX:
            MAX = e
    return MAX

def grade(*lists):
    return [get_max(elems) for elems in zip(*lists)]

grade([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85])
# [99, 100, 77, 96, 87]

CodePudding user response：

To simplify it for you think in terms of an matrix

[ 
  1, 5, 7
  2, 3, 15  
  8, 2, 12 
]

Now basically what you want is the maximum among each column in this matrix

def highest_grade_among_list(gradelist1,gradelist2,gradelist3):
    #ensure the list are of same length
    if len(gradelist1) != len(gradelist2) or len(gradelist2) != len(gradelist3) or len(gradelist1) != len(gradelist3):
        return "Error: lists are not of same length"
    else:
        grade_matrix = []
        grade_matrix.append(gradelist1)
        grade_matrix.append(gradelist2)
        grade_matrix.append(gradelist3)

        

        max_grade_in_col = 0
        result = []

        for i in range(len(gradelist1)):
            for j in range(len(grade_matrix)):
                
                if grade_matrix[j][i] > max_grade_in_col:
                    max_grade_in_col = grade_matrix[j][i]

            result.append(max_grade_in_col)
            max_grade_in_col = 0

        return result

if __name__ == '__main__':
    print(highest_grade_among_list([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85]))

CodePudding user response：

When you want to transpose plain Python lists, zip is your friend. You can get the result with a comprehension:

[max(lst) for lst in zip([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85])]

gives as expected:

[99, 100, 77, 96, 87]

CodePudding user response：

If only max() is not allowed

def grade(l1, l2, l3):
    return [sorted(z)[-1] for z in zip(l1,l2,l3)]
    
print(grade([99,88,77,92,44],[80,100,65,48,87],[75,95,70,96,85]))
# [99, 100, 77, 96, 87]