QCustomPlot clear Data

[HafsaElif]

@kshegunov I dont want to set empty data . I was searching for fallowing code which is shared by mrjj.

[indu]

Hi,

I'm facing some issue with ui->qcustom->graph(0)->data()->clear();. It is not working for me.
Data container is not getting cleared, even if i call clear() and then replot().
Pls help.
Thank you.

[oaeide]

I have the same problem as indu2. Calling clear() and replot(), nothing happens

[Marcel92]

Try ui->yourPlot->clearPlottables();

[david_808]

clearPlottables() does not work because it deletes the object entirely.

[mrjj]

@david_808

Hi
Maybe ask the author of customplot about how to do it correctly then?

[Scarab]

Try:

for( int g=0; g<pq_plot->graphCount(); g++ )
{
    pq_plot->graph(g)->data().data().clear();
}
pq_plot->replot();

don't know why to use ->data().data() but it works for me.

[Joel Bodenmann]

@Scarab said in QCustomPlot clear Data:

don't know why to use ->data().data() but it works for me.

The type returned by QCPGraph::data() is a shared pointer to the data container. Both the shared pointer as well as the object the shared pointer is pointing to have a clear() function:

• If you do pq_plot->graph(g)->data().clear() you are calling QSharedPointer::clear().
• If you do pq_plot->graph(g)->data()->clear() you're calling QCPGraphDataContainer::clear() - which is what you actually want.

Calling pq_plot->graph(g)->data().data().clear() (as per your example) effectively calls QCPGraphDataContainer::clear() because QSharedPointer::data() returns the raw pointer managed by the shared pointer.
Therefore, pq_plot->graph(g)->data().data().clear() and pq_plot->graph(g)->data()->clear() are equivalent.

I hope this helps to prevent confusion for people that come across this in the future.

[Jamshid]

@Joel-Bodenmann It was so helpful for me, thanks.

[QtTester]

@Joel-Bodenmann said in QCustomPlot clear Data:

iner::clear()
I have tested for one hour, the memory grow from 8192k to 9600k，when i call clear()，the memory is still 9600k, seems not release.