Python pyqtgraph how to set x and y axis limits on

问题:

I would like to know how I can set the x and y axis limits that are displayed for a pyqtgraph.GraphicsWindow.addPlot object. I need to display a lot of data inside a loop (hence using pyqtgraph) but I would rather preallocate my axes as opposed to allowing autorange to potentially enhance speed. As an example,

from pyqtgraph.Qt import QtGui, QtCore
import numpy as np
import pyqtgraph as pg
app = QtGui.QApplication([])
win = pg.GraphicsWindow(title="My plotting examples")
win.resize(1000,600)
win.setWindowTitle('pyqtgraph example: Plotting')
p1 = win.addPlot(title="plot1")
p2 = win.addPlot(title="plot2")
curve1 = p1.plot(pen='y')
curve2 = p1.plot(pen='r')
curve3 = p2.plot(pen='b')
x = np.linspace(0,10,1000)
x_current = x[0]
p1.setXRange((5,20), padding=0)
for i in range(1,len(x)):
    x_current = np.append(x_current,x[i])
    curve1.setData(x_current,np.sin(x_current))
    curve2.setData(x_current,np.cos(x_current))
    curve3.setData(x_current,np.tan(x_current))
    app.processEvents()

if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

The problem lies in the line p1.setXRange((5,20),padding=0). This results in the error: TypeError: setXRange() takes at least 3 arguments (3 given)

I think this should be a very simple question, just setting the axis ranges before plotting.

回答1:

As the error message indicates, you have not supplied the correct number of arguments to setXRange(). The correct line should look like:

p1.setXRange(5, 20, padding=0)

Documentation here: http://www.pyqtgraph.org/documentation/graphicsItems/viewbox.html#pyqtgraph.ViewBox.setXRange

回答2:

Michael.

The easiest way would be to simply specify your ranges as elements of a list. Replace the p1.setXRange with something like this:

p1.setRange(xRange=[5,20])

And that's it!

Check the documentation of this class in: http://www.pyqtgraph.org/documentation/graphicsItems/viewbox.html#pyqtgraph.ViewBox.setRange

回答3:

The questions asks how to set a limit to the view which none of the responses to this point answers. For others who come across this the view of the plot can be limited to a section of the axis like this:

p1.plotItem.vb.setLimits(xMin=a, xMax=b, yMin=c, yMax=d)

Documentation: http://www.pyqtgraph.org/documentation/graphicsItems/viewbox.html