I’ve done a lot of GitHub searching but I can’t find an erlang/elixir data structure similar to Java’s SortedMap . I’ve been using ETS :sortedset but the performance hasn’t been sufficient for my needs. Anyone got any suggestions ? Need to do iterations and multiple lookups …

There is an Erlang gb_tree that is built in . For ordered iteration, there is an iterator/1, and to_list/1 can be used with Enum I think. gb_sets is also available. Sadly it’s interface isn’t compatible with Elixir pipes, because the data structure is the last argument but an Elixir wrapper should…

Have you considered using this library? [image] ord_map Ordered map for Elixir lang

I’m not sure from the project docs it’s doing what I need.

Had a look. I’ll throw in a couple of examples now and maybe benchmark later. Create new : :gb_trees.empty Populate with 10 elements : gb = 1..10 |> Enum.reduce(:gb_trees.empty, fn x,acc -> :gb_trees.insert(x,x,acc) end) Iterating elements : {k,v,next} = :gb_trees.next(iter) I will mention …

If you need the high performance, you could still leverage ets for direct access and use a separate data structure just for iteration of the keys, but that does get cumbersome. Nifs are tricky :slight_smile: you can take a look at this (very similar) nif I write to wrap a C data structure (also a s…

This probably calls for a generic Rustler-based Elixir library that bridges various Rust data structures to Elixir code. In your case that’d be Rust’s BTreeMap . Discord have a sorted set library with bindings to Rust – not a map but still, in case you need this one as well. You can also just take a…

Yeah everyone speaks well of Rust for native code - I haven’t taken the time to learn it so worried about the cognitive load but I do know C/C++ . Should probably watch Scroggin’s talk again but I’m spending so much time on beam/infrastructure I’ve not much chance to learn a new language. Excuses. E…

Thanks @mpope some good points there. exor_filter/c_src/xor_filter_nif.c at master · mpope9/exor_filter · GitHub yeah good example of resource allocation/deallocation - at least it’s reasonably straightforward in BEAM compared to say for example writing a Java native extension. Good point about the …

Can you share the use case for an ordered map? I super curious!

Typical use case would be to match people looking to rent or let property by geographic area. Perform a periodic rollup across all users. Remove users who had already been matched. Have tried with ETS but was only able to process 80,000 per second. Personal challenge is to find a way to match 200,00…

Elixir Programming Language Forum

Map with ordered keys

Questions & Help Questions

japplegame August 3, 2020, 7:40am 4

If you need custom ordering, consider AVLTree