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

jon
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online: p. 186 But...
New
jesse050717
Title: Web Development with Clojure, Third Edition, pg 116 Hi - I just started chapter 5 and I am stuck on page 116 while trying to star...
New
sdmoralesma
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159 When I execute the command: user=&gt; (create-...
New
swlaschin
The book has the same “Problem space/Solution space” diagram on page 18 as is on page 17. The correct Problem/Solution space diagrams ar...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
AndyDavis3416
@noelrappin Running the webpack dev server, I receive the following warning: ERROR in tsconfig.json TS18003: No inputs were found in c...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
digitalbias
Title: Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana on (page 64) If you follow the defau...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
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

Other popular topics Top

AstonJ
If it’s a mechanical keyboard, which switches do you have? Would you recommend it? Why? What will your next keyboard be? Pics always w...
New
PragmaticBookshelf
Ruby, Io, Prolog, Scala, Erlang, Clojure, Haskell. With Seven Languages in Seven Weeks, by Bruce A. Tate, you’ll go beyond the syntax—and...
New
Exadra37
Please tell us what is your preferred monitor setup for programming(not gaming) and why you have chosen it. Does your monitor have eye p...
New
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
New
PragmaticBookshelf
Use WebRTC to build web applications that stream media and data in real time directly from one user to another, all in the browser. ...
New
AstonJ
Was just curious to see if any were around, found this one: I got 51/100: Not sure if it was meant to buy I am sure at times the b...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
PragmaticBookshelf
Programming Ruby is the most complete book on Ruby, covering both the language itself and the standard library as well as commonly used t...
New
AstonJ
This is cool! DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON We just witnessed something incredible: the largest open-s...
New

Sub Categories: