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1 vote

I am working on a multithreaded application where the acquisition and chart display run on different threads. I am attempting to collect samples and plot only when I have 100 samples available to have less resource consumption and keep the application responsive. However, when I change the number of samples in the block, my FIFO capacity seems to change, allowing significantly less amount of samples than the ones I need. The current FIFO capacity should allow for at least 16 mins worth of data, but it only shows less than a second

If I set the block size to 1 (single sample appending) I obtain the results I need, but I am seeing performance issues in other areas of the program, hence the need of appending in blocks.

See the attachments for more clarity. Any suggestions?

EDIT: Adding code

private void DisplayNPD()
            XyDataSeries<float, float> npdRawDataSeries = new XyDataSeries<float, float>();
            int fifoSize = 1000000;
            npdRawDataSeries.FifoCapacity = fifoSize;
            npdRawData_RS.DataSeries = npdRawDataSeries;

            double npdRaw = 0;
            bool successfulDequeue = false;
            int samplesQueued = 0;
            int samplesInBlock = 100;
            float[] rawSamples = new float[samplesInBlock];
            float[] time = new float[samplesInBlock];

            while (!ImagingSession.terminateThreads)
                if (ImagingSession.laserOnOff && !graphRestarted)
                    int npdElementsInQueue = npdDisplayQueue.Count;
                    if (npdElementsInQueue > 0)
                        successfulDequeue = npdDisplayQueue.TryDequeue(out npdRaw);

                    if (successfulDequeue)
                        currentTime = graphStopwatch.ElapsedMilliseconds * 0.001;
                        time[samplesQueued] = (float) currentTime;
                        rawSamples[samplesQueued] = (float) (npdRaw * 1000);

                        if (samplesQueued == samplesInBlock)
                            using (npdRawDataSeries.SuspendUpdates())
                                npdRawDataSeries.Append(time, rawSamples);
                            samplesQueued = 0;

                            if (currentTime > upperLimit)
                                lowerLimit = upperLimit;
                                upperLimit += xAxisWidth;
0 votes

I want to build a column chart but I got the following error:

ERROR TypeError: Cannot read property ‘append’ of undefined

The error happened in line #42.

My code:

export class OutputAmplitudeComponent implements OnInit, OnDestroy {

constructor(@Inject(SETTING_SERVICE) private settingService: SettingService, private cdr: ChangeDetectorRef) {}

ngOnInit() {        
                this.settingService.registerSetting(HarmonicAmpSetting).pipe(takeUntil(this.ngUnsubHarmonicData)).subscribe(setting => {
                    const OutputAmplitudeData = setting.value;

                    for (let x = 1; x < this.numberOfOutput; x++) {
                        if (this.OutputMode === 'Voltage') {
                            if (phaseNum === 1) {
                      [x-1].voltage1 = OutputAmplitudeData[x];
                            } else if (phaseNum === 2) {
                      [x-1].voltage2 = OutputAmplitudeData[x];
                            } else if (phaseNum === 3) {
                      [x-1].voltage3 = OutputAmplitudeData[x]; 
                        } else if (this.OutputMode === 'Current') {
                            if (phaseNum === 1) {
                      [x-1].current1 = OutputAmplitudeData[x];
                            } else if (phaseNum === 2) {
                      [x-1].current2 = OutputAmplitudeData[x];
                            } else if (phaseNum === 3) {
                      [x-1].current3 = OutputAmplitudeData[x];


    var phaseNum1 = [];
    var xData = [];
    for (let x = 1; x < this.numberOfOutput; x++) {
        if ( != null &&[x-1] != null) {
            phaseNum1[x - 1] = parseFloat([x - 1].voltage1);
            xData[x - 1] = x;
            if (!isNaN(phaseNum1[x - 1])) {
            } else {
                console.log("No num");

async sciChartInit() {

    const { wasmContext, sciChartSurface } = await SciChartSurface.create("chart");

    var phaseNum1 = [];
    var xData = [];
    this.dataSeries1 = new XyDataSeries(wasmContext);
    for (let x = 1; x < this.numberOfOutput; x++) {
        this.dataSeries1.append(x, x);

    const xAxis = new NumericAxis(wasmContext);
    const yAxis = new NumericAxis(wasmContext);

    const rendSeries1 = new StackedColumnRenderableSeries(wasmContext);
    rendSeries1.fill = "#dc443f";
    rendSeries1.stroke = "green";
    rendSeries1.strokeThickness = 1;
    rendSeries1.dataSeries = this.dataSeries1;
    rendSeries1.stackedGroupId = "one";

    const verticallyStackedColumnCollection = new StackedColumnCollection(wasmContext);
    verticallyStackedColumnCollection.dataPointWidth = 0.5;
    verticallyStackedColumnCollection.animation = new ScaleAnimation({ duration: 1000, fadeEffect: true });

    sciChartSurface.chartModifiers.add(new ZoomExtentsModifier(), new ZoomPanModifier(), new MouseWheelZoomModifier());

        new LegendModifier({
            placement: ELegendPlacement.TopRight,
            orientation: ELegendOrientation.Horizontal,
            showLegend: true,
            showCheckboxes: true,
            showSeriesMarkers: true
    return { wasmContext, sciChartSurface };

I don’t understand what is undefined and why.

Thank you.

  • ETS Ong asked 3 years ago
  • last active 3 years ago
0 votes

Is there an efficient way to append a subset of an array to a DataSeries? Manually looping with Append is slow (as expected). Iterating over an IEnumerable introduces overhead. I’ve read in the performance tips and tricks section that “Arrays have the biggest impact as these can be indexed using unsafe code”. The help documentation doesn’t list an Append overload specifically for an array so I assume the type is checked within the method.

I am reusing arrays whenever possible; however, my arriving data is not always the same length. In order to reduce allocations and garbage collection, I make use of Memory, Span, and ArraySegment elsewhere in my project. This allows me to pool and reuse memory. I have not found any DataSeries.Append overloads that would accept any of these types or otherwise allow me to specify the usable range of the array. Please let me know if I’ve overlooked something.

Thank you.

0 votes


I have a fast column renderable series where a column is added each hour. When the first column is added, it renders approximately half the graph (regardless of zoom), which is unintended. Once the data point for the second hour is added, the column collapses down to the space of the hour (as we would want). Why is the first column rendering too wide? Am I failing to set a parameter that is required?

Below is my series setup:

 val uoColumnSeries =
        generateColumnRenderableSeries(LABEL_ID_UO, uoColumnDataSeries, SolidBrushStyle(uoColumnColor))
    uoColumnSeries.dataPointWidth = .95

Attached is how the data renders with 1 point (zoomed in and out), and data render once second point (of height 0) is added. The graph in question is the column graph at the top in yellow.


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