Use RectMode to select and get data from plots?

[Blot Romain]

Hi,

I would like to customize the setMouseMode in order to do a multiple data selection tool instead of zooming. Can you give me some advices to start a subclass or something.?

Thank a lot.

Romain

[Blot Romain]

I forgot to tell that I mainly work with timeseries and not images. So ROI don't seems to do what I want.
Thanks for your help

[Luke Campagnola]

I would not recommend doing anything with setMouseMode. Instead, you can make a ViewBox subclass that extends the mouseDragEvent method. You can handle a left-button drag to make the selection, and use the original mouseDragEvent to handle middle- and right-button drags. Something along the lines of:

  class MyViewBox(pg.ViewBox):

      def mouseDragEvent(self, ev):

          if ev.button() != QtCore.Qt.LeftButton:

              return pg.ViewBox.mouseDragEvent(self, ev)

          ev.accept()

          # handle selection here..
 

Luke

[Blot Romain]

Thank you for your answer!

So I can do something like this :

class MyViewBox(pg.ViewBox):
     
    def mouseDragEvent(self, ev):
       

        if ev.button() == QtCore.Qt.RightButton:
            ev.ignore()   
        else:
            pg.ViewBox.mouseDragEvent(self, ev)
        
        ev.accept()
        pos = ev.pos()
       
        if ev.button() == QtCore.Qt.RightButton:
            self.updateScaleBox(ev.buttonDownPos(), ev.pos())
           
            if ev.isFinish(): 
                self.rbScaleBox.hide()
                ax = QtCore.QRectF(Point(ev.buttonDownPos(ev.button())), Point(pos))
                ax = self.childGroup.mapRectFromParent(ax)
                MouseRectCoords =  ax.getCoords() 
                self.dataSelection(MouseRectCoords)     
            else:
                self.updateScaleBox(ev.buttonDownPos(), ev.pos())
         
    def dataSelection(self,MouseRectCoords):
        print MouseRectCoords     

However, how can I get the Items (curve, scatter ....) into dataSelection?

Thanks,

Romain

[Luke Campagnola]

On Mon, Jan 27, 2014 at 10:46 AM, Blot Romain <blot....@gmail.com> wrote:

Thank you for your answer!

So I can do something like this :

class MyViewBox(pg.ViewBox):
     
    def mouseDragEvent(self, ev):
       

        if ev.button() == QtCore.Qt.RightButton:
            ev.ignore()   
        else:
            pg.ViewBox.mouseDragEvent(self, ev)
        
        ev.accept()
        pos = ev.pos()
       
        if ev.button() == QtCore.Qt.RightButton:
            self.updateScaleBox(ev.buttonDownPos(), ev.pos())
           
            if ev.isFinish(): 
                self.rbScaleBox.hide()
                ax = QtCore.QRectF(Point(ev.buttonDownPos(ev.button())), Point(pos))
                ax = self.childGroup.mapRectFromParent(ax)
                MouseRectCoords =  ax.getCoords() 
                self.dataSelection(MouseRectCoords)     
            else:
                self.updateScaleBox(ev.buttonDownPos(), ev.pos())
         
    def dataSelection(self,MouseRectCoords):
        print MouseRectCoords     

Sure! It's a little awkward reusing updateScaleBox for this purpose, but I suppose it works..

 

However, how can I get the Items (curve, scatter ....) into dataSelection?

See QGraphicsScene.items:
http://qt-project.org/doc/qt-4.8/qgraphicsscene.html#items-10

 

[Blot Romain]

Thanks again for your help, I would not have been able to think about it alone.
So I made the code attached to illustrate what I try to do. Now I can select points dragging a rectangle with the mouse right click, which is a good step for me :). However, I can not find a way to change the color of the selected points. I failed to use the scatterPlotItem attributs and classes to do it.
Do you have an idea?

Romain

[Luke Campagnola]

On Wed, Jan 29, 2014 at 8:05 AM, Blot Romain <blot....@gmail.com> wrote:

Thanks again for your help, I would not have been able to think about it alone. So I made the code attached to llustrate what I try to do. Now I can select points dragging a rectangle with the mouse right click, which a good step for me :). However, I can not find a way to change the color of the selected points. I failed to use the scatterPlotItem attributs and classes to do it. Do you have an idea?

I recommend you have a look at examples/ScatterPlot.py. Clicking on any of the plots there changes the outline of any points under the mouse cursor. You should be able to use the same approach..

Luke

 

[Blot Romain]

Hi, again you were right the scatterplot example put me the right path.

Very sorry to bother you again but I have a problem with pg.GraphicsScene.items() now. As you commented in GraphicScene.py, the original class from QtGui has a bug and it looks like it is what happen to me. The example attached previously stop to work when I increase the number of data points, exemple :

a  = np.arange(100)
b  = np.arange(100)

The problem is that pg.GraphicsScene.items doesn't always return the same number and kind of Item Object. Sometimes it works but sometimes not. Do you have an idea on how I can fix that?

thanks

Romain

[Blot Romain]

Also, I wonder why pg.GraphicsScene.items() doesn't return anything for a very large number of points.

[Blot Romain]

Oh I see that the main issue is that GraphicsScene.items doesn't like to have a QRectF in local coords.

[Luke Campagnola]

On Tue, Feb 4, 2014 at 5:25 AM, Blot Romain <blot....@gmail.com> wrote:

Oh I see that the main issue is that GraphicsScene.items doesn't like to have a QRectF in local coords.

Correct; this should be mapped to scene coordinates first.

Is there still an issue remaining that you need help with? I couldn't really follow..

[Blot Romain]

Thanks again Luke. For now I have my stuff working ok.