Deleting item from a map

Questions / Help
, , ,
1

How can i delete an item from a map of three arguments.

%{
  [:a, ["a1", "a2"]] => 1,
  [:b, ["b1"]] => 2,
  [:c, ["c1", "c2", "c3"]] => 1
}

How can I delete an item from this map? Let’s say I want to delete the key :a

I have tried using Map.drop and Map.delete but it doesn’t work on this example.

Thanks

2

Both of them expect the complete key, not just a part of it. :a is not a key in your map, it’s just an atom, which happens to be included in one of the keys of your map.

filter_atom = :a

%{
  [:a, ["a1", "a2"]] => 1,
  [:b, ["b1"]] => 2,
  [:c, ["c1", "c2", "c3"]] => 1
}
|> Enum.filter(fn 
  {[^filter_atom, _], _v} -> false
  _ -> true
end)
|> Map.new()
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3

It’s really helpful, may I know whats this operator for ^filter_item. What’s the role of ^? what is it called in Elixir?

4

https://hexdocs.pm/elixir/Kernel.SpecialForms.html#^/1

2 Likes