Quickstart example for NeuralNetwork not working

[hansvana]

Tested with @0.4.3 and @0.5.0 (see notes)

Example of the problem: p5js editor

Steps to reproduce:

• Open a new sketch on the P5js editor (or codepen.io, or local, it didn't matter) with ml5 linked.
• Copy the Creating data in real-time example from the docs.
• Run

Problem:

• The training seems to run, but the visor draws no line in the graph, the result comes out as

0: Object
  red-ish: NaN
  label: "red-ish"
  confidence: NaN
1: Object
  blue-ish: NaN
  label: "blue-ish"
  confidence: NaN

Notes:

• I did some research. Commenting out line 24 and 25 actually makes the training run. 😄

const inputs = {
    r: item.r, 
    //g: item.g, 
    //b: item.b
};

On @0.5.0 this then also provides a correct prediction. On @0.4.3 the training runs but ends with a high loss and the confidence is NaN.

[joeyklee]

@hansvana - Ahhh I had a look and I think I spot the issue.

If all of the values of g are "0" then the normalization runs into some issues which may be leading to the problem that the training isn't occurring.

const data = [
  {r:255, g:0, b:0, color:'red-ish'},
  {r:254, g:0, b:0, color:'red-ish'},
  {r:253, g:0, b:0, color:'red-ish'},
  {r:0, g:0, b:255, color:'blue-ish'},
  {r:0, g:1, b:254, color:'blue-ish'},
  {r:0, g:1, b:253, color:'blue-ish'},
];

This is definitely a bug that we will need to address. Thanks for surfacing this!

[langfan94]

@hansvana - Ahhh I had a look and I think I spot the issue.

If all of the values of g are "0" then the normalization runs into some issues which may be leading to the problem that the training isn't occurring.

const data = [
  {r:255, g:0, b:0, color:'red-ish'},
  {r:254, g:0, b:0, color:'red-ish'},
  {r:253, g:0, b:0, color:'red-ish'},
  {r:0, g:0, b:255, color:'blue-ish'},
  {r:0, g:1, b:254, color:'blue-ish'},
  {r:0, g:1, b:253, color:'blue-ish'},
];

This is definitely a bug that we will need to address. Thanks for surfacing this!

ml5js/ml5-library#973 (comment)

If the NN expects a string, I think sholud give a notice, or explicit cast.

pull request to change neural-network.md
#ml5js/ml5-library#1010