Elixir：在列表中查找中间项

Question

I'm trying to learn Elixir. In most other languages i've battled with, this would be an easy task.

However, i can't seem to figure out how to access a list item by index in Elixir, which i need for finding the median item in my list. Any clarification would be greatly appreciated!

Answer 1

You will want to look into Enum.at/3 .

a = [1,2,3,4,5]
middle_index = a |> length() |> div(2)
Enum.at(a, middle_index)

Note: This is expensive as it needs to traverse the entire list to find the length of the list, and then traverse halfway through the list to find what the actual element is. Generally speaking, if you need random access to an item in a list, you should be looking for a different data structure.

Answer 2

This is how I would do it:

Enum.at(x, div(length(x), 2))

Enum.at/3 retrieves the value at a particular index of an enumerable. div/2 is the equivalent of the Python 2.x / integer division.