I am trying to create a live updated non-uniform heatmap with uniform xStep but non-uniform yStep. But I got color mapping problem when I tried to create the non-uniform heatmap. The color showing in the chart doesn’t map with the ColorMap value. Below are my codes:
Draw the non-uniform heatmap:
const SPECTROGRAM_HEIGHT = 256;
const SPECTROGRAM_WIDTH = 100;
const { sciChartSurface, wasmContext } = await SciChartSurface.create("spectrogram-chart-root");
const xAxis = new NumericAxis(wasmContext, {
axisTitle: "Frequency",
axisTitleStyle: {
fontSize: CHART_STYLE.AXIS_FONT_SIZE,
fontFamily: "sans-serif",
fontWeight: "bold"
},
labelStyle: {
fontSize: CHART_STYLE.LABEL_FONT_SIZE,
fontFamily: "sans-serif"
},
labelFormat: ENumericFormat.Decimal,
labelPrecision: 6,
cursorLabelFormat: ENumericFormat.Decimal,
cursorLabelPrecision: 6,
drawMajorBands: false,
});
const yAxis = new NumericAxis(wasmContext, {
axisTitle: "Time",
axisTitleStyle: {
fontSize: CHART_STYLE.AXIS_FONT_SIZE,
fontFamily: "sans-serif",
fontWeight: "bold"
},
labelStyle: {
fontSize: CHART_STYLE.LABEL_FONT_SIZE,
fontFamily: "sans-serif"
},
drawMajorBands: false,
});
// Add XAxis and YAxis
sciChartSurface.xAxes.add(xAxis);
sciChartSurface.yAxes.add(yAxis);
const colorMap = new HeatmapColorMap({
minimum: -200,
maximum: -50,
gradientStops: [
{ offset: 1, color: COLORS.DARK_RED },
{ offset: 0.8, color: COLORS.RED },
{ offset: 0.6, color: COLORS.YELLOW },
{ offset: 0.5, color: COLORS.GREEN },
{ offset: 0.4, color: COLORS.BLUE },
{ offset: 0.01, color: COLORS.DARK_BLUE },
{ offset: 0, color: "Transparent" },
]
});
// Create a Heatmap Data-series. Pass heatValues as a number[][] to the UniformHeatmapDataSeries
zValues = Array.from(Array(SPECTROGRAM_HEIGHT), () => Array(SPECTROGRAM_WIDTH).fill(-200));
const heatmapSeries = new NonUniformHeatmapRenderableSeries(wasmContext, {
dataSeries: new NonUniformHeatmapDataSeries(wasmContext, { zValues: zValues, xCellOffsets: getHeatmapXOffset, yCellOffsets: getHeatmapYOffset }),
colorMap: colorMap,
useLinearTextureFiltering: true,
fillValuesOutOfRange: true,
});
// Add heatmap to the chart
sciChartSurface.renderableSeries.add(heatmapSeries);
I simply return the index for testing in the getHeatmapXOffset and getHeatmapYOffset functions:
const getHeatmapXOffset = (index) => {
return index;
};
const getHeatmapYOffset = (index) => {
return index;
};
I fill the zValues array with the minimum value -200, but the data displayed in the chart is COLORS.YELLOW. I don’t understand what’s wrong.
- Quyen Sy asked 1 year ago
- last active 1 year ago
I was looking at the example given at this link for NonUniformHeatmapDataSeries in SciChart. In this example, the width and height of heatmap is given as h=4 and w=7. As I understand h is for Y axis and w is for X axis and data[,] is for Z axis. However, the counts in actual data filled for these axis are not matching wight h and w.
var xRangeMapping = new int[] { 0, 10, 20, 26, 36, 60, 72, 84 }; // 8 points for w
var yRangeMapping = new int[] { 100, 250, 390, 410, 600 }; // 5 points for h
What is the purpose of extra points added at first place (0 and 100)? Are these required to set the starting point for both axis?
Here is the code given at above link:
int w = 7, h = 4;
var data = new double[h, w];
double maxValue = double.MinValue;
for (int x = 0; x < w; x++)
for (int y = 0; y < h; y++)
{
data[y, x] = 3.5 * ((h - y) * (w - x));
maxValue = Math.Max(maxValue, data[y,x]);
}
var xRangeMapping = new int[] { 0, 10, 20, 26, 36, 60, 72, 84 };
var yRangeMapping = new int[] { 100, 250, 390, 410, 600 };
var heatmapDataSeries = NonUniformHeatmapDataSeries<int, int, double>(data, i => xRangeMapping[i], i => yRangeMapping[i]);
// Apply the Heatmap DataSeries to a FastNonUniformheatmapRenderableSeries
var heatmapRenderableSeries = new FastUniformHeatmapRenderableSeries()
{
ColorMap = new HeatmapColorPalette()
{
Maximum = maxValue,
Minimum = 0,
GradientStops = // exercise left to the reader
}
};
- Anil Soman asked 5 years ago
- last active 5 years ago
