Python Finding Index of Maximum in List

Question

def main():
    a = [2,1,5,234,3,44,7,6,4,5,9,11,12,14,13]
    max = 0
    for number in a:
        if number > max:
            max = number
    print max

if __name         


        

Answer 1

A simple one liner of:

max( (v, i) for i, v in enumerate(a) )[1]

This avoids having to .index() the list after.

Answer 2

In my code I would use this:

>>> max(enumerate(a),key=lambda x: x[1])[0]
3

Answer 3

You can use enumerate to also give you an index while iterating through a list:

>>> a = [2, 1, 5, 234, 3, 44, 7, 6, 4, 5, 9, 11, 12, 14, 13]
>>> maxIndex, maxNumber = 0, 0
>>> for index, number in enumerate(a):
        if number > maxNumber:
            maxIndex = index
            maxNumber = number

>>> maxIndex, maxNumber
(3, 234)

Answer 4

Use the argmax method of the numpy.array object.

import numpy as np
np.array(a).argmax()

Answer 5

If you aren't allowed to use the built in index() function, just iterate with an index, instead of using a foreach loop.

for i in range(len(a)):
    if a[i] > max:
        max = a[i]
        maxIndex = i

Answer 6

this is way simpler

x.index(max(x)) #where x is your list