π **Question**: How to find the index of the median element in a Python list? Something like `argmedian()`

?

In case you need a quick refresher, I have written this tutorial on finding the median itself (but not yet its index):

π **Recommended**: 6 Ways to Get the Median of a Python List

## Solution

A multi-liner solution to get the index of the median index is to first sort the list, take the mid-element from the sorted list, and search the index of the median using the `list.index()`

method. This finds the index of the first occurrence of the median.

Here’s a code snippet that does that:

def median_index(lst): sorted_lst = sorted(lst) mid = len(lst) // 2 median = sorted_lst[mid] return lst.index(median) print(median_index([10, 1, 5])) # 2 print(median_index([10, 1, 5, 99, 100, 100])) # 3 print(median_index([10, 1, 5, 99, 100, 100, 0])) # 0

This is a Python function that takes a list of numbers as input and returns the index of the median element of the list. Here’s how the code works:

`def median_index(lst)`

: This line defines a function called`median_index`

that takes a list`lst`

as input.`sorted_lst = sorted(lst)`

: This line creates a new list called`sorted_lst`

that contains the same elements as the input list`lst`

, but sorted in ascending order using the built-in`sorted()`

function.`mid = len(lst) // 2`

: This line calculates the index of the median element in the original unsorted list`lst`

by dividing the length of the list by 2 using the floor division operator`//`

.`median = sorted_lst[mid]`

: This line assigns the value of the median element in the sorted list`sorted_lst`

to a new variable called`median`

. If the length of the list is odd, this will be the element at the index`mid`

. If the length of the list is even,`mid`

will be the index of the element to the left of the middle two elements, and`median`

will be the leftmost of those two elements.`return lst.index(median)`

: This line returns the index of the median element in the original unsorted list`lst`

by using the built-in`index()`

function to find the index of the first occurrence of the`median`

value in`lst`

.- The
`print()`

statements at the end of the code call the`median_index()`

function with different input lists and print the output to the console. For example,`print(median_index([10, 1, 5]))`

will print`2`

because the median element of the input list`[10, 1, 5]`

is`5`

, and its index in the list is`2`

.

## Python One-Liner to Find the Index of Median

I love Python one-liners. β₯οΈ

So, here’s the same code condensed in a single line of Python code that finds the index of the median element in the `lst`

using `lst.index(sorted(lst)[len(lst)//2])`

def median_index(lst): return lst.index(sorted(lst)[len(lst)//2])

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