reversescale doesn't reverse colorbar on contour plot with coloring='heatmap'

[harupy]

Bug

reversescale: True doesn't reverse the colorbar on a contour plot with {contours: {coloring: 'heatmap'}}.

In the plot below, the colorbar indicates the red region has larger values, but it actually has smaller values.

Code

var data = [{
  z: [[10, 10.625, 12.5, 15.625, 20],
      [5.625, 6.25, 8.125, 11.25, 15.625],
      [2.5, 3.125, 5., 8.125, 12.5],
      [0.625, 1.25, 3.125, 6.25, 10.625],
      [0, 0.625, 2.5, 5.625, 10]],
  x: [-9, -6, -5 , -3, -1],
  y: [0, 1, 4, 5, 7],
  type: 'contour',
  contours: {
    coloring: 'heatmap'
  },
  reversescale: true,
}];

var layout = {
  title: 'Setting the X and Y Coordinates in a Contour Plot'
};

Plotly.newPlot('myDiv', data, layout);

Codepen

https://codepen.io/harupy/pen/bGNgBOz

[harupy]

Without {contours: {coloring: 'heatmap'}}, it works.

Code

var data = [{
  z: [[10, 10.625, 12.5, 15.625, 20],
      [5.625, 6.25, 8.125, 11.25, 15.625],
      [2.5, 3.125, 5., 8.125, 12.5],
      [0.625, 1.25, 3.125, 6.25, 10.625],
      [0, 0.625, 2.5, 5.625, 10]],
  x: [-9, -6, -5 , -3, -1],
  y: [0, 1, 4, 5, 7],
  type: 'contour',
  reversescale: true,
}];

var layout = {
  title: 'Setting the X and Y Coordinates in a Contour Plot'
};

Plotly.newPlot('myDiv', data, layout);

Codepen

https://codepen.io/harupy/pen/NWPddqQ

[harupy]

plotly.js/src/traces/contour/colorbar.js

Lines 22 to 28 in adf9bee

	if(coloring === 'heatmap') {
	var cOpts = extractOpts(trace);
	opts._fillgradient = trace.colorscale;
	opts._zrange = [cOpts.min, cOpts.max];
	} else if(coloring === 'fill') {
	opts._fillcolor = colorMap;
	}

Do we need to flip the colorscale here like below?

    if(coloring === 'heatmap') {
        var cOpts = extractOpts(trace);

        opts._fillgradient = cOpts.reversescale ?
            Colorscale.flipScale(cOpts.colorscale) :
            cOpts.colorscale;

        opts._zrange = [cOpts.min, cOpts.max];
    } else if(coloring === 'fill') {
        opts._fillcolor = colorMap;
    }

It seems to be working.

the json to produce the plot above:

{
  "data": [
    {
      "z": [
        [10, 10.625, 12.5, 15.625, 20],
        [5.625, 6.25, 8.125, 11.25, 15.625],
        [2.5, 3.125, 5, 8.125, 12.5],
        [0.625, 1.25, 3.125, 6.25, 10.625],
        [0, 0.625, 2.5, 5.625, 10]
      ],
      "x": [-9, -6, -5, -3, -1],
      "y": [0, 1, 4, 5, 7],
      "type": "contour",
      "contours": {
        "coloring": "heatmap"
      },
      "reversescale": true
    }
  ]
}

[etpinard]

Thanks for reporting!

[harupy]

@etpinard Thanks!