Neuro-Evolution with TensorFlow.js! about tensorflow-js-examples

[nsthorat]

Yeah actually we should probably do this in the library, I'll send a fix but for now just slice it (slice is shallow so is cheap) :)

[nsthorat]

Hey Dan!

What kind of strange behavior are you seeing?

One thing I would note is you shouldn't override the value like this: https://github.com/shiffman/Tensorflow-JS-Examples/blob/master/04_neuro_evolution/nn.js#L55

Actually because of the way we're sharing these TypedArrays you're in place mutating the underlying values in the Tensor :/. One simple solution is to use arraySync instead of dataSync since we do a copy. Or you can copy the output of dataSync to a new Float32Array (using a new Float32Array and TypedArray.set).

[nsthorat]

BTW, if you use the arraySync route you have to deal with the dimensionality of weights, maybe use the second approach of copying the Float32Array output of the dataSync.

[shiffman]

Aha, this is the issue! (Big thanks to @meiamsome who also discovered this.) I didn't realize that dataSync() doesn't copy the data! So I was shallow instead of deep copying and the new population was sharing weights across models! An extra slice() function to copy sorts out the issue.

let arr = w[i].dataSync().slice();

More soon!

[nsthorat]

FYI, we decided not to do this in the library. TypedArray.slice() is shallow but in JS that's not a lazy copy, it will copy all the numbers to the new array slowing down dataSync(). I'm going to clarify this in documentation, but unfortunately we're not going to make the change upstream so you'll have to slice the TypedArray in your code.

[shiffman]

No worries, I appreciate all the info and help! Having this handled by tf.js is by no means necessary for what I'm working on.

[shiffman]

Closing as the example is working great now! More to come...

[parweb]

Well thank you, I find this conversation after torturing my natural neural brain for the entire afternoon.
exactly what need !

By the way the repository location code of @shiffman change

https://github.com/shiffman/Tensorflow-JS-Examples/blob/master/04_neuro_evolution_flappy/nn.js