Given a list of N integers, the task is to write a Python program to find the index of the maximum element in the Python list.
Example:
Input: [ 2, 4, 6, 1, 8, 5, 3 ]
Output: Index of the max element in a list is 4
Explanation: The max element is 8 and its position is 4.Input: [ 10, 1, 5, 3, 8, 9, 7 ]
Output: Index of the max element in a list is 0
Explanation: The max element is 10 and its position is 0.
Get the index of the max value without using in-built functions
We are given list of integers. Our task is to find the index of the maximum element.
Python3
#list of numberslist1 = [ 2, 4, 6, 1, 8, 5, 3 ]ind = 0 #ind variable to store the index of maximum value in the listmax_element = list1[0]for i in range (1,len(list1)): #iterate over array if list1[i] > max_element: #to check max value max_element = list1[i] ind = i#print the index of maximum elementprint("Index of the maximum element in the list is: ",ind) |
Index of the maximum element in the list is: 4
Time Complexity: O(n),
Auxiliary space: O(1)
Get the index of the max value in the list using the max() and index()
Here we are given a Python list and our task is to find the index of the maximum element so we are finding the maximum element using max() and then finding the index of that element using index() in Python.
Python3
# Defining a listl = [1, 4, 3, 7, 8, 10, 2]# Calculating the maximum element # in the listm = max(l)# Finding the index of the maximum# elementprint("Index of the max element in a list is", l.index(m)) |
Index of the max element in a list is 5
Time Complexity: O(n),
Auxiliary space: O(1)
Get the index of the max value in the list using the loop
Here we are given a list and our task is to find the index of the maximum element so we are finding the maximum element using max() and then finding the index of that element using a while loop and iterating over the list.
Python3
# Defining a listl = [1, 4, 3, 7, 8, 10, 2]# Calculating the maximum element # in the listm = max(l)# Finding the index of the maximum # elementi = 0while(i < len(l)): if l[i] == m: print("Index of the max element in a list is", i) break i += 1 |
Index of the max element in a list is 5
Time Complexity: O(n),
Auxiliary space: O(1)
Find the index of the max value in a list using the enumerate function
Here we are given a list and our task is to find the index of the maximum element so we are iterating over the list using the enumerate() function as the index, pair. If we have the same element at two positions we will return both indexes.
Python3
# Defining the listl = [12, 22, 4, 3, 7, 8, 10, 22]# Finding maximum elementm = max(l)# iterating over the list like index,# item pairfor i, j in enumerate(l): if j == m: print("Index of the max element in a list is", i) |
Index of the max element in a list is 1 Index of the max element in a list is 7
Time Complexity: O(n),
Auxiliary space: O(1)
Find the index of the max value in a list using Pandas
Here we are given a list and our task is to find the index of the maximum element so we are finding its index using idxmax() in the Pandas module.
Python3
# importing the required libraryimport pandas as p# Defining the listl = [12, 4, 3, 7, 8, 10, 22]# Printing the index of the maximum elementprint("Index of the max element in a list is", p.Series(l).idxmax()) |
Output:
Index of the max element in a list is 6
Time Complexity: O(n),
Auxiliary space: O(1)
Find the index of the max value in a list using Numpy
Here we are given a list and our task is to find the index of the maximum element so we are finding its index using argmax() in the Numpy module.
Python3
# importing the required libraryimport numpy# Defining the listl = [12, 4, 3, 7, 8, 10, 22]# argmax returns the max element's indexidx = numpy.argmax(l)print("Index of the max element in a list is", idx) |
Output:
Index of the max element in a list is 6
Time Complexity: O(n),
Auxiliary space: O(1)
Sort the list in descending order
One new approach that is not discussed in the article is to use the built-in sorted() function to sort the list in descending order, and then access the first element of the sorted list to get the index of the maximum item in the list.
Python3
# Defining a listl = [1, 4, 3, 7, 8, 10, 2] # Sorting the list in descending ordersorted_list = sorted(l, reverse=True)# Accessing the first element of the sorted listmax_element = sorted_list[0]# Finding the index of the maximum elementprint("Index of the max element in a list is", l.index(max_element)) |
Index of the max element in a list is 5
Time Complexity: O(nlogn),
Auxiliary space: O(1)
Find index of maximum item in list Using Recursion
We are using recursive method to find the index of maximum element in the list.
Python3
# Recursive function to find the index of maximum of elementdef FindIndex(itr,ind,list1): if itr == len(list1): #base Condition print("Index of the maximum element in the list is : ",ind) return if list1[itr] > list1[ind]: #max condition ind = itr FindIndex(itr+1,ind,list1) #Recursive Function call return#Driver codelist1 = [2,4,1,9,0,8]FindIndex(0,0,list1)#This code is Contributed by Jyothi Pinjala. |
Index of the maximum element in the list is : 3
Time Complexity: O(n),
Auxiliary space: O(n)
