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"""
generates 'example_gradient_plot.png'
"""
import numpy as np
import pyqtgraph as pg
import pyqtgraph.exporters as exp
from pyqtgraph.Qt import QtCore, QtGui, QtWidgets, mkQApp
class MainWindow(pg.GraphicsLayoutWidget):
""" example application main window """
def __init__(self):
super().__init__()
self.resize(420,400)
self.show()
# Prepare demonstration data
raw = np.linspace(0.0, 2.0, 400)
y_data1 = ( (raw+0.1)%1 ) ** 4
y_data2 = ( (raw+0.1)%1 ) ** 4 - ( (raw+0.6)%1 ) ** 4
# Example 1: Gradient pen
cm = pg.colormap.get('CET-L17') # prepare a linear color map
cm.reverse() # reverse it to put light colors at the top
pen = cm.getPen( span=(0.0,1.0), width=5 ) # gradient from blue (y=0) to white (y=1)
# plot a curve drawn with a pen colored according to y value:
curve1 = pg.PlotDataItem( y=y_data1, pen=pen )
# Example 2: Gradient brush
cm = pg.colormap.get('CET-D1') # prepare a diverging color map
cm.setMappingMode('diverging') # set mapping mode
brush = cm.getBrush( span=(-1., 1.) ) # gradient from blue at -1 to red at +1
# plot a curve that is filled to zero with the gradient brush:
curve2 = pg.PlotDataItem( y=y_data2, pen='w', brush=brush, fillLevel=0.0 )
for idx, curve in enumerate( (curve1, curve2) ):
plot = self.addPlot(row=idx, col=0)
plot.getAxis('left').setWidth(25)
plot.addItem( curve )
self.timer = pg.QtCore.QTimer( singleShot=True )
self.timer.timeout.connect(self.export)
self.timer.start(100)
def export(self):
print('exporting')
exporter = exp.ImageExporter(self.scene())
exporter.parameters()['width'] = 420
exporter.export('example_gradient_plot.png')
mkQApp("Gradient plotting example")
main_window = MainWindow()
## Start Qt event loop
if __name__ == '__main__':
pg.exec()
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