Sean Moriarity seanmor5

Genetic Algorithm in Nx

Preface

After writing Genetic Algorithms in Elixir, I had no real hopes or expectations that numerical computing would become a focus for Elixir. However, to my surprise, the Nx project developed rather quickly, and proved that Elixir could be used for practical machine learning and numerical computing applications. While I don't have any plans (yet) of reworking the examples in my book to take advantage of the acceleration enabled by Nx, EXLA, and other projects, I feel it's necessary to show how you could go about rewriting your genetic algorithms to take advantage of Elixir's new numerical computing libraries.

Introduction

Nx is a numerical computing library for Elixir which supports the creation and manipulation of multi-dimensional arrays (called tensors in the API), automatic differentiation, and just-in-time (JIT) compilation to CPU, GPU, and other accelerators via pluggable backends and compilers. Nx opens up a realm of possibilities for Elixir dev

	<!-- livebook:{"persist_outputs":true} -->

	# zip create benchmark

	```elixir
	Mix.install([
	{:benchee, "~> 1.0"}
	])
	```

	defmodule Client do
	def main(pid) do
	cmd = IO.gets("Enter a command: ") \|> String.trim()

	case String.split(cmd) do
	["show"] ->
	key = self()

	Task.async(fn ->
	send(pid, {:list, key, self()})

	main = fn ->
	cmd = IO.gets("Enter a command: ") \|> String.trim()

	case String.split(cmd) do
	["show"] ->
	todos = Process.get(:todos) \|\| []
	IO.puts(Enum.join(todos, "\n"))

	["create" \| rest] ->
	todos = Process.get(:todos) \|\| []

	main = fn ->
	cmd = IO.gets("Enter a command: ") \|> String.trim()

	case cmd do
	"1" ->
	todos = Process.get(:todos) \|\| []
	IO.puts(Enum.join(todos, "\n"))

	"2" ->
	todos = Process.get(:todos) \|\| []

	defmodule Day4 do
	import Nx.Defn

	def part1() do
	File.read!("aoc/4.txt")
	\|> parse_input()
	\|> play_bingo()
	\|> find_winning_board()
	end

	defmodule Day3 do
	# Since my last answer wasn't purely Nx, I'm going
	# to try to stick to Nx as much as is possible, but
	# we don't have string manipulation stuff so that will
	# have to be done in Elixir
	import Nx.Defn

	def part1 do
	File.read!("aoc/3.txt")
	\|> parse_input()

	# part 1
	File.read!('aoc/2.txt')
	\|> String.replace("\r", "") # i am on windows right now :(
	\|> String.split("\n")
	\|> Enum.map(fn line ->
	[direction, amt] = String.split(line)
	amt_int = String.to_integer(amt)

	case direction do
	"forward" ->

	# Part 1
	File.read!('aoc/1.txt')
	\|> String.replace("\r", "") # i am on windows right now :(
	\|> String.split("\n")
	\|> Enum.map(&String.to_integer/1)
	\|> Nx.tensor()
	\|> then(fn x ->
	Nx.greater(Nx.slice_axis(x, 1, Nx.size(x) - 1, 0), Nx.slice_axis(x, 0, Nx.size(x) - 1, 0))
	end)
	\|> Nx.sum()