Ultimately I’d like to update the values of keys in myMap based on whether the key is in myList and in myOtherList: myList = ["a", "b", "c"] myOtherList = ["b"] myMap = %{"a" => "no", "b" => "no", "c" => "no"} Enum.each(myList, fn e -> case Enum.member?(myOtherList, e) do true -> Map.…

The solution was solved in another topic: [image] Update a map that is outside scope of an iterator Questions map_A = Enum.reduce(map_A, %{}, fn {k, v}, out → if Enum.member?(Map.keys(map_B), x) == true) do Map.put(out, k, “yes”) else Map.put(out, k, “no”…

I suggest using if else for this. Also, to mutate your map you have to use explicit assignment, so my_map = if (...). Oh, and in Elixir snake_case is the most widely used convention.

defmodule Demo do def replace_with(list, value) do fn {x , _} = pair -> cond do Enum.member?(list, x) -> {x, value} true -> pair end end end end myOtherList = ["b"] myMap = %{"a" => "no", "b" => "no", "c" => "no"} newMap = myMap |> Enum.map(Demo.replac…

Will myList always be identical to Map.keys(myMap)? Or will they diverge? Will Map.values(myMap) always be identical to a list of "no"? Or might there be other values? In the following solution, I will assume, that myList and Map.keys(myMap) might be different, while the values all have to be "no".…

To me it seems peculiar that the original code completely ignores all the values that are already in the Map - what is the point of having a Map then? myOtherList = ["b"] myMap = %{"a" => "no", "b" => "no", "c" => "no"} difference = Map.keys(myMap) -- myOtherList new_value = "yes" newMap = (for …

Let me be more specific by redefining the problem: For each key in map_A (we don’t care about the values) get another known map (for example sake: map_B) which is referenced by the key at map_A and test whether any of the keys in map_B matches some variable x. If match, update value at key in map_A …

[image] JupiterIO1: and I assume in this case that any iterator will not allow this. T There is no “iterator”. for is a comprehension . Simply speaking it consumes an enumerable and produces a list (or whatever else :into identifies) - it’s an expression like everything else in Elixir, not a s…

Stop thinking of “variables”- all values in Elixir are immutable. However identifiers can be rebound to new values. So the only thing that can “vary” is the value the identifier is bound to - not the value itself. Imperative languages are about PLace-Oriented Programming (PLOP) - in functional prog…

You are right. As much as I have learnt and understood this concept, I should be more specific with my language. ty

Elixir Programming Language Forum

Update value in map based on Enum.member? check

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sanswork September 8, 2018, 8:11pm 3

Check out Enum.reduce