[SOLVED]QWT plot doesn’t like my array

toho71

I try to use the QWt plot graph and I tried a little example.
But it crashes in the

@curve1->setData(x,y1,100);@

//Error msg
error: no matching function for call to ‘QwtPlotCurve::setData(double [100], double [100], int)’

My code

@ ui->qwtPlot->setTitle("TWO CURVES");
ui->qwtPlot->setParent(ui->tab_4);

double x[100], y1[100];

for (int i = 0; i < 100; i++)
{
    x[i] = i;
    y1[i] = 10-0.1*i*i;
}

// add curves
QwtPlotCurve *curve1 = new QwtPlotCurve("Curve 1");

// copy the data into the curves
curve1->setData(x,y1,100);
curve1->attach(ui->qwtPlot);

ui->qwtPlot->replot();
@

Anyone

lgeyer

Your application doesn't crash, your code raises a compilation error. Most probably because there is no such method setData() which takes two double arrays and an int as a parameter. Take another look at the "documentation":http://qwt.sourceforge.net/class_qwt_plot_series_item.html#adba072515f7c71c923985882129878c4.

toho71

Yes your right its a compilation problem.
And i tried a setRawData and it worked as I expected.

I never used this plot widget before.

koahnig

As Lukas suggested QwtPlotCurve does not have the method setData with this parameter list. You have to use setRawSamples or setSamples in your case. setRawData is not available either according to the documentation.

toho71

Yes rawSampel is the thing.
Is there anyone with a very simpel example

koahnig

qwt comes with examples. Did you try them?

toho71

yepp and the problem is solved

vezprog

plotcurve->setSamples() works just fine. I have used it multiple times. Create your X and Y QVector<double> 's and just feed them in.

AstroFloyd

"Here":http://programmingexamples.net/wiki/Qt/QWT/Plot is a simple but complete example.