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