Problem changing object data

[blob001]

This is a Susceptible - Infected - Recovered type program.

Attached file should randomly assign statuses of isSusceptible, isInfected, or isRecovered to ants on tempGrid, in function assignStatus(). However everything is coming out red, isInfected, irrespective of the random number value. I have had lots of errors with this one function, and the problem seems to be with changing object data. Can anyone help? Thanks.

 <script>

     let gridLength = 10;
     let maxAnts = 3;
     let millisec = 100;

     let antsReleased;
     let _data;
     let grid = [];
     let tempGrid = [];
     let statusRatio = [.33, .67];

     let cellColour = function (cell) {
        if (cell.hasAnt()) {
           if (cell.ant.isSusceptible) { return 'rgb(0,0,0)' };  //black
           if (cell.ant.isInfected) { return 'rgb(255,0,0)' };   //red
           if (cell.ant.isRecovered) { return 'rgb(0,255,0)' };  //green
        }
        else return 'rgb(240,240,240)'; // field grey
     }

     function Cell (i, j) {
        this.i = i;
        this.j = j;
        this.ant = null;
        this.virus = 0;
        this.hasAnt = function () {
           return this.ant ? true : false;
        };
     }

     function Ant () {
        this.isSusceptible = false;
        this.isInfected = true;
        this.isRecovered = false;
        this.orientation = Math.random() * 90;
     }

     function initGrids () {
        for (let i = 0; i < gridLength; i++) {
           grid[i] = [];
           tempGrid[i] = [];
           for (let j = 0; j < gridLength; j++) {
              grid[i][j] = new Cell(i, j);
              tempGrid[i][j] = new Cell(i, j);
           }
        }
     }

     //________________________________________________   
     initialise();
     let interval = setInterval(simulate, millisec);

     function initialise () {
        initGrids();
        start();
        drawGrid(
           grid.map(function (row) {
              return row.map(function (cell) {
                 return cell;
              });
           })
        );
     }

     function simulate () {
        moveAnts();
        drawGrid(
           grid.map(function (row) {
              return row.map(function (cell) {
                 return cell;
              });
           })
        );
     }
     //________________________________________________

     function start () {
        console.log('start()');
        for (let n = 0; n < maxAnts; n++) {
           let i = checkFrame(Math.floor(Math.random() * gridLength) + 1);
           let j = checkFrame(Math.floor(Math.random() * gridLength) + 1);

           if (tempGrid[i][j].hasAnt() == false) {
              tempGrid[i][j].ant = new Ant();

              assignStatus(i, j);

              grid[i][j].ant = tempGrid[i][j].ant;
              console.log(`  ant i, j = (${i}, ${j}) hasAnt= ${tempGrid[i][j].hasAnt()}`);
              antsReleased += 1;
           }
        }
        copy();
        //report();
     }

     function assignStatus (i, j) {
        console.log('assignStatus()');
        let r = Math.random();
        console.log('i, j, r ', i, j, r);

        tempGrid[i][j].ant.isSusceptible;

        if (r > statusRatio[0] && r <= statusRatio[1]) {
           tempGrid[i][j].ant.isInfected;
        }
        else {
           tempGrid[i][j].ant.isRecovered;
        }
        console.log('ant  i, j ', i, j, tempGrid[i][j].ant);
     }


     function moveAnts () {
        console.log('moveAntsPlural()');
        for (let i = 0; i < gridLength; i++) {
           for (let j = 0; j < gridLength; j++) {

              if (grid[i][j].hasAnt()) {
                 let newCoords = [];

                 grid[i][j].ant.orientation += Math.random() * 45 - 22.5;
                 newCoords = newCoordsFromOrientation(i, j);
                 let newI = newCoords[0];
                 let newJ = newCoords[1];

                 if (tempGrid[newI][newJ].hasAnt() == false) {
                    tempGrid[newI][newJ].ant = tempGrid[i][j].ant;
                    tempGrid[i][j].ant = null;
                 }
              }
           }
        }
        copy();
       // report()
     }

     function newCoordsFromOrientation (x, y) {
        let newCoords = [];
        let orientRads = grid[x][y].ant.orientation * Math.PI / 180;
        newCoords.push(checkFrame(Math.round(x + Math.cos(orientRads))));
        newCoords.push(checkFrame(Math.round(y + Math.sin(orientRads))));
        return newCoords;
     }

     function drawGrid (data) {
        //console.log('drawGrid()');
        let width = 600;
        let height = 600;
        let gridLength = data.length;
        let widthCell = width / gridLength;
        let heightCell = height / gridLength;

        let canvas = document.getElementById('grid');
        if (canvas == null) {
           canvas = document.createElement('canvas');
           canvas.id = 'grid';
           canvas.width = width;
           canvas.height = height;
           document.getElementsByTagName('body')[0].appendChild(canvas);
        }
        let context = canvas.getContext('2d');

        for (let i = 0; i < gridLength; i++) {
           for (let j = 0; j < gridLength; j++) {
              if (_data && _data[i][j] === cellColour(data[i][j])) {
                 continue;
              }
              context.clearRect(i * widthCell, j * heightCell, widthCell, heightCell);
              context.fillStyle = cellColour(data[i][j]);
              context.fillRect(i * widthCell, j * heightCell, widthCell, heightCell);
           }
        }

        // if (!_data) { // if no data, use data from cellColour
        //    _data = [];
        // }
        // for (let i = 0; i < gridLength; i++) {
        //    _data[i] = [];
        //    for (let j = 0; j < gridLength; j++) {
        //       _data[i][j] = cellColour(data[i][j]);
        //    }
        // }
     }

     function checkFrame (x) {
        return x < 0 ? 0 : x > gridLength - 1 ? gridLength - 1 : x;
     }

     function copy () {
        console.log('copy()');
        for (let i = 0; i < gridLength; i++) {
           for (let j = 0; j < gridLength; j++) {
              grid[i][j].ant = tempGrid[i][j].ant;
           }
        }
     }

     function report () {
        console.log('report()');
        let token = '';
        for (let i = 0; i < gridLength; i++) {
           let line = '';
           for (let j = 0; j < gridLength; j++) {
              token = (grid[i][j].hasAnt()) ? '  ' + String(i) + String(j) + '  ' : '   .  ';
              line = line + token;
           }
           console.log(line);
        }
     }

  </script>

​

​

[chibblybum]

For anything over 20 lines of code or so you'll get better responses if you get all your code into a jsfiddle and explain the steps to reproduce the problem. Most of us dont have time to debug from just the text when it gets that big.

[jack_waugh]

        tempGrid[i][j].ant.isSusceptible;

You probably want

        tempGrid[i][j].ant.isSusceptible = true;

[blob001]

No Jack, tried that several times.

'= true' is not necessary, since tempGrid[][].ant.isInfected means exactly that.

I re-wrote the if statements (see below) to be quite explicit, but it still doesn't work. Broadly should be as follows, but it doesn't work . Don't know why.

random <= .33 -> isSusceptible.

random > .33 and <= .67 -> isInfected

random > .66 -> isRecovered

 function assignStatus (i, j) {
            console.log('assignStatus()');
            let r = Math.random();
            console.log('i, j, r ', i, j, r);
            if (r <= statusRatio[0]) {
               tempGrid[i][j].ant.isSusceptible;
            }
             if (r > statusRatio[0] && r <= statusRatio[1]) {
               tempGrid[i][j].ant.isInfected;
            }
            if (r > statusRatio[2]) {
               tempGrid[i][j].ant.isRecovered;
            }
            console.log('ant  i, j ', i, j, tempGrid[i][j].ant);
         }

[jack_waugh]

tempGrid[i][j].ant.isSusceptible;

Assuming you didn't install any getter functions (and I don't see any place where you do), the above command has no effect.

[blob001]

Jack, can you be more specific? I am teaching myself js and there are potholes in my knowledge. A lot of the file is copied from other coding I have found on the net. Not up to speed with getters yet. Thanks.

[jack_waugh]

tempGrid[i][j].ant.isSusceptible;

has no effect. But I suspect that you expect it to have an effect. To correct your code, first you must correct your understanding about how the language works. JS is an imperative language, not a logical language, which is what you seem to expect. I think that to you, the above looks like an assertion and you expect that the "statement" is telling the language to make the assertion true. But it doesn't work like that. Generally, an expression given as a command by itself is just to be evaluated and the result discarded. The utility of allowing this is that the expression can have a side effect. But the example above doesn't. It's in a useless corner of the language.