tvanderpol

tvanderpol

Genetic Algorithms in Elixir: Ch 3 chromosome metadata not maintained (~p 144)

After creating the Chromosome type and updating the one_max script, the size attribute isn’t carried through. I realised that in both crossover() and mutation() the new Chromosome instance isn’t being populated by the relevant parent / existing chromosome. I updated the crossover code to

    {c1, c2} = {
      %Chromosome{p1 | genes: h1 ++ t2},
      %Chromosome{p2 | genes: h2 ++ t1}
    }

and similar for mutation:

      %Chromosome{chromosome | genes: Enum.shuffle(chromosome.genes)}

That sorted it out.

Unrelated I’m pretty sure there were some typos in the area where we updated all the framework code to carry the Problem definition through (initialise’s arguments were missing something, from memory) but I didn’t take notes.

Cheers,
Thomas

Marked As Solved

seanmor5

seanmor5

Author of Genetic Algorithms in Elixir

Thanks for pointing this out. I’ll go back through and ensure the metadata is retained correctly throughout implementations. I hope these mistakes aren’t detracting from your experience with the book! I appreciate the help in making the book better for everybody.

Also Liked

patrickdm

patrickdm

I’ve also stumped upon the missing size when I tried to use it in crossover/2 as p1.size instead of recalculating length(p1.genes) at each iteration. I took a while to figure out it was not retained after initializing the chromosome’s population.

About the chromosome update you mention, we can discuss if you really want the age to increase after a crossover (when you get a kind of new chromosome) or if we should consider a new generation only after a mutation. But I think this are not so relevant aspects in respect of the main code’s objective.

Similar consideration goes for the silly optimization I made in evaluate/3, when I opted to use the precalculated fitness for the last sorting step:

...
|> Enum.sort_by(& &1.fitness, &>=/2)
tvanderpol

tvanderpol

To be honest my Elixir is pretty rusty so having to do a bit of debugging and making sure the code is doing what I think it’s doing is added value for me right now. :smiley:

Where Next?

Popular Pragmatic Bookshelf topics Top

belgoros
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84: bundle exec sequel...
New
ianwillie
Hello Brian, I have some problems with running the code in your book. I like the style of the book very much and I have learnt a lot as...
New
Mmm
Hi, build fails on: bracket-lib = “~0.8.1” when running on Mac Mini M1 Rust version 1.5.0: Compiling winit v0.22.2 error[E0308]: mi...
New
gilesdotcodes
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
New
brian-m-ops
#book-python-testing-with-pytest-second-edition Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...
New
hazardco
On page 78 the following code appears: <%= link_to ‘Destroy’, product, class: ‘hover:underline’, method: :delete, data: { confirm...
New
kolossal
Hi, I need some help, I’m new to rust and was learning through your book. but I got stuck at the last stage of distribution. Whenever I t...
New
ggerico
I got this error when executing the plot files on macOS Ventura 13.0.1 with Python 3.10.8 and matplotlib 3.6.1: programming_ML/code/03_...
New
bjnord
Hello @herbert ! Trying to get the very first “Hello, Bracket Terminal!" example to run (p. 53). I develop on an Amazon EC2 instance runn...
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’...
1033 17470 383
New
malloryerik
Any thoughts on Svelte? Svelte is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue...
New
DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
PragmaticBookshelf
Rust is an exciting new programming language combining the power of C with memory safety, fearless concurrency, and productivity boosters...
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
New
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1143 25883 760
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
PragmaticBookshelf
Author Spotlight: Tammy Coron @Paradox927 Gaming, and writing games in particular, is about passion, vision, experience, and immersio...
New
PragmaticBookshelf
Author Spotlight: Sophie DeBenedetto @SophieDeBenedetto The days of the traditional request-response web application are long gone, b...
New

Sub Categories: