Creating array in function

cameronnichols

`function Perceptron(n,lines){
  this.weights = new Array(lines);
  console.log(this.weights);
  for (var i = 0; i < this.weights.length; i++){
    this.weights[i] = new Array(n);
  }
  this.lr = 0.002;
  for (var i = 0; i < this.weights.length; i++){
    for (var j = 0; j < this.weights[i].length; j++){
      this.weights[i][j] = random(-1,1);
    }
  }
  this.guesses = new Array(lines);
  for (var i = 0; i < this.guesses.length; i++){
    this.guesses[i] = function(inputs){
      sum = 0;
      console.log(n+','+lines);
      console.log(this.weights.length);
      for (var j = 0; j < this.weights[i].length; j++){
        sum += inputs[j]*this.weights[i][j];
      }
      return sign(sum);
    }
  }
}`

Here's my output: https://gyazo.com/318a9f2982f0a52efc735cfdb410caa2

As you can see, I first define 'this.weights' as a new array, with length of 'lines' and yes, both arguments to the function are numbers.

But for some reason, I can log this.weights, and it says it's undefined, and I guess that's because all of the elements are undefined?

But it throws an error at line 85, which is simply console.log(this.weights.length);

If I take that line out, then for (var j = 0; j < this.weights[i].length; j++){ throws an error, how can I fix this?

GoToLoop

https://forum.Processing.org/two/discussion/15473/readme-how-to-format-code-and-text

After a quick reading, I've spotted 2 serious JS logical errors in your array of functions.
There can still be others though: :-SS

• You create your inner functions inside a loop and access the iterator i inside them as a closure.
• However, given only 1 i variable exists, when any of those inner functions are eventually invoked later, i is gonna be equal to this.guesses.length always. That is, the last value assigned to i!

• My fix proposal: declare iterator variable i w/ let instead of var. *-:)

• The other error is that you access this inside your looped-created inner functions.

• However, when again they're eventually invoked, that this is gonna point to the global window, rather than pointing to Perceptron's this instance!
• My fix proposal: Use lambda fat arrow functions instead of regular 1s for such cases: this.guesses[i] = inputs => { :>

1. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let#Cleaner_code_in_inner_functions
2. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions#No_binding_of_this

GoToLoop

• I guess I'm wrong about my 2nd guess.
• As long as those inner functions are called via a variable holding a reference of a Perceptron's instance, the this inside them gonna point to the latter. :-\"
• Nonetheless, declaring those inner anonymous functions using lambda fat arrow syntax are still valid & safer. $-)
• Don't forget to edit your post in order to better format your posted code. L-)

cameronnichols

Thanks for the information on let and =>

So basically let is how to define a local variable, and => is a way to define an inner function?

GoToLoop

• let is 1 of the 5 ways we can declare variables in JS.
• The lambda fat arrow => function is similar to use bind(this) over a regular function:

https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

cameronnichols

Ok, thank you! I'm a bit new to java (started about 3-4 days ago)

GoToLoop

Your sketch is in JS, not Java... ~O)