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

brianokken
Many tasks_proj/tests directories exist in chapters 2, 3, 5 that have tests that use the custom markers smoke and get, which are not decl...
New
Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
edruder
I thought that there might be interest in using the book with Rails 6.1 and Ruby 2.7.2. I’ll note what I needed to do differently here. ...
New
herminiotorres
Hi @Margaret , On page VII the book tells us the example and snippets will be all using Elixir version 1.11 But on page 3 almost the en...
New
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
New
adamwoolhether
When trying to generate the protobuf .go file, I receive this error: Unknown flag: --go_opt libprotoc 3.12.3 MacOS 11.3.1 Googling ...
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 found an issue in Chapter 7 regarding android:backgroundTint vs app:backgroundTint. How to replicate: load chapter-7 from zipfile i...
New
adamwoolhether
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New

Other popular topics Top

PragmaticBookshelf
Andy and Dave wrote this influential, classic book to help their clients create better software and rediscover the joy of coding. Almost ...
New
AstonJ
Or looking forward to? :nerd_face:
502 14279 275
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
foxtrottwist
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
husaindevelop
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
New
New
sir.laksmana_wenk
I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc. However, I don’t...
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New

Sub Categories: