How to Get Duplicates In A List In Elixir?

In Elixir, one way to get duplicates in a list is to use the Enum.group_by function to group duplicate elements together, and then filter out groups with a count of 1. Another approach is to iterate over the list and keep track of elements that have already been seen, adding them to a separate list if they appear again. Both methods can help identify and extract duplicates from a given list in Elixir.

What is the expected behavior when duplicate elements are encountered in a list in elixir?

In Elixir, when duplicate elements are encountered in a list, they are kept as separate elements in the list rather than being automatically removed or combined. This means that duplicates will be present in the final list unless specifically removed or filtered out by the developer using functions like Enum.uniq in Elixir.

How to identify duplicate values in a list in elixir?

To identify duplicate values in a list in Elixir, you can use the Enum.reduce/3 function along with a Map to keep track of the counts of each element in the list. Here's an example implementation:

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defmodule ListUtils do
  def find_duplicates(list) do
    list
    |> Enum.reduce(%{}, fn elem, acc ->
      Map.update(acc, elem, 1, &(&1 + 1))
    end)
    |> Map.filter(fn {_key, count} -> count > 1 end)
    |> Map.keys()
  end
end

list = [1, 2, 3, 2, 4, 5, 3, 6, 7, 8, 2]
duplicates = ListUtils.find_duplicates(list)
IO.inspect(duplicates) # Output: [2, 3]

In this implementation, the find_duplicates function takes a list as input and uses Enum.reduce to create a Map where the keys are elements from the list and the values are the counts of each element. Then, it filters the Map to only keep elements with count greater than 1 (i.e., duplicates) and retrieves the keys which are the duplicate values in the list.

How to remove duplicates from a list in elixir?

One way to remove duplicates from a list in Elixir is to use the Enum module along with the Enum.uniq/1 function. Here is an example:

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list = [1, 2, 2, 3, 4, 4, 5]
unique_list = Enum.uniq(list)

IO.inspect(unique_list)  # Output: [1, 2, 3, 4, 5]

Another way to remove duplicates from a list in Elixir is to use recursion. Here is an example of a recursive function that removes duplicates from a list:

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defmodule ListUtils do
  def remove_duplicates([], acc), do: Enum.reverse(acc)
  def remove_duplicates([head | tail], acc) do
    if Enum.member?(acc, head) do
      remove_duplicates(tail, acc)
    else
      remove_duplicates(tail, [head | acc])
    end
  end
end

list = [1, 2, 2, 3, 4, 4, 5]
unique_list = ListUtils.remove_duplicates(list, [])

IO.inspect(unique_list)  # Output: [1, 2, 3, 4, 5]