joustava

joustava

Genetic Algorithms in Elixir: Code throws error (page 111)

Not sure if I’m doing something wrong here, but it seems that this piece of code will throw errors:

def fitness_function(chromosome) do
    target = 'ILoveGeneticAlgorithms'
    encrypted = 'LIjs`B`k`qlfDibjwlqmhv'
    cipher = fn word, key -> Enum.map(word, & rem(&1 ^^^ key, 32768)) end
    key =
      chromosome.genes
      |> Enum.map(&Integer.to_string/1)
      |> Enum.join("")
      |> String.to_integer(2)

      guess = List.to_string(cipher.(encrypted, key))
      String.jaro_distance(target, guess)
end

As

String.jaro_distance(target, guess)

Doesn’t expect ‘charlists’ but binaries

** (FunctionClauseError) no function clause matching in String.Unicode.graphemes/1

    The following arguments were given to String.Unicode.graphemes/1:

        # 1
        'ILoveGeneticAlgorithms'

    Attempted function clauses (showing 1 out of 1):

        def graphemes(binary) when is_binary(binary)

    (elixir 1.10.3) lib/elixir/unicode/unicode.ex:252: String.Unicode.graphemes/1
    (elixir 1.10.3) lib/string.ex:2488: String.jaro_distance/2
    (genetic 0.1.0) lib/genetic.ex:24: anonymous fn/2 in Genetic.evaluate/3
    (elixir 1.10.3) lib/enum.ex:1396: Enum."-map/2-lists^map/1-0-"/2
    (genetic 0.1.0) lib/genetic.ex:23: Genetic.evaluate/3
    (genetic 0.1.0) lib/genetic.ex:116: Genetic.evolve/6
    scripts/code_breaker.exs:39: (file)

I’m running this on:

⟩ elixir --version
Erlang/OTP 23 [erts-11.0.2] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Elixir 1.10.3 (compiled with Erlang/OTP 23)

Not sure if something has changed recently regarding this issue.

Also, it seems the capture operator ‘&’ is in the wrong place in the book and should be moved before the call to ‘rem’ otherwise a

** (ArithmeticError) bad argument in arithmetic expression: rem(#Function<1.106933999/1 in CodeBreaker.fitness_function/1>, 32768)
    :erlang.rem(#Function<1.106933999/1 in CodeBreaker.fitness_function/1>, 32768)
    scripts/code_breaker.exs:16: anonymous fn/2 in CodeBreaker.fitness_function/1
    (genetic 0.1.0) lib/genetic.ex:24: anonymous fn/2 in Genetic.evaluate/3
    (elixir 1.10.3) lib/enum.ex:1396: Enum."-map/2-lists^map/1-0-"/2
    (genetic 0.1.0) lib/genetic.ex:23: Genetic.evaluate/3
    (genetic 0.1.0) lib/genetic.ex:116: Genetic.evolve/6
    scripts/code_breaker.exs:33: (file)

will occur.
I think on the next page in the iex example it is the correct way.

First Post!

adkelley

adkelley

Strings in Elixir are inserted between double quotes. Therefore change: target = 'ILoveGeneticAlgorithms' to: target = "ILoveGeneticAlgorithms"

Where Next?

Popular Pragmatic Bookshelf topics Top

jimschubert
In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...
New
johnp
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’. In particula...
New
sdmoralesma
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159 When I execute the command: user=&gt; (create-...
New
jskubick
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
jskubick
I’m under the impression that when the reader gets to page 136 (“View Data with the Database Inspector”), the code SHOULD be able to buil...
New
jskubick
I found an issue in Chapter 7 regarding android:backgroundTint vs app:backgroundTint. How to replicate: load chapter-7 from zipfile i...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
New
taguniversalmachine
It seems the second code snippet is missing the code to set the current_user: current_user: Accounts.get_user_by_session_token(session["...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New
roadbike
From page 13: On Python 3.7, you can install the libraries with pip by running these commands inside a Python venv using Visual Studio ...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1052 22283 402
New
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
PragmaticBookshelf
From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...
New
AstonJ
Thanks to @foxtrottwist’s and @Tomas’s posts in this thread: Poll: Which code editor do you use? I bought Onivim! :nerd_face: https://on...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
AstonJ
Saw this on TikTok of all places! :lol: Anyone heard of them before? Lite:
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
New
AstonJ
If you’re getting errors like this: psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New

Sub Categories: