How to plot two real-time data in one single plot in PyQtGraph?

Question

I am willing to get 2 random data and plot it in the same Widget using PyQtGraph in a real-time way. I want them to show up as Red and Blue dots. However, after a hard time,

Answer 1

While pyqtgraph is a great package from a functionality perspective, unfortunately the documentation is lacking, and you really just have to dig in to the code and start to understand the structure of the objects.

When you call:

p1 = win.addPlot() 

This returns a reference to a PlotItem, at which point you can now add multiple PlotDataItems to this p1 object (see semi-useful structure diagram here : http://www.pyqtgraph.org/documentation/plotting.html#organization-of-plotting-classes )

So when you call:

curve1 = p1.plot()

This adds PlotDataItem #1, ... you now need to call it again to get a second reference to use:

curve2 = p1.plot()

This becomes PlotDataItem #2, which you can then use for the 2nd setData method in your plot() method to call during update(). Which would look like:

def plot():

    #Blue Dots
    curve1.setData(dataBlue, pen=None, symbol='o', symbolPen=None, symbolSize=4, symbolBrush=('b'))
    #Red Dots
    curve2.setData(dataRed, pen=None, symbol='o', symbolPen=None, symbolSize=4, symbolBrush=('r'))