92 lines
2.5 KiB
Python
92 lines
2.5 KiB
Python
# -*- coding: utf-8 -*-
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import initExample ## Add path to library (just for examples; you do not need this)
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import pyqtgraph as pg
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from pyqtgraph.Qt import QtCore, QtGui
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import numpy as np
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from time import perf_counter
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app = pg.mkQApp()
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plt = pg.PlotWidget()
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app.processEvents()
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## Putting this at the beginning or end does not have much effect
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plt.show()
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## The auto-range is recomputed after each item is added,
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## so disabling it before plotting helps
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plt.enableAutoRange(False, False)
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def plot():
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start = perf_counter()
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n = 15
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pts = 100
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x = np.linspace(0, 0.8, pts)
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y = np.random.random(size=pts)*0.8
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for i in range(n):
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for j in range(n):
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## calling PlotWidget.plot() generates a PlotDataItem, which
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## has a bit more overhead than PlotCurveItem, which is all
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## we need here. This overhead adds up quickly and makes a big
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## difference in speed.
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#plt.plot(x=x+i, y=y+j)
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plt.addItem(pg.PlotCurveItem(x=x+i, y=y+j))
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#path = pg.arrayToQPath(x+i, y+j)
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#item = QtGui.QGraphicsPathItem(path)
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#item.setPen(pg.mkPen('w'))
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#plt.addItem(item)
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dt = perf_counter() - start
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print(f"Create plots tooks {dt * 1000:.3f} ms")
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## Plot and clear 5 times, printing the time it took
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for i in range(5):
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plt.clear()
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plot()
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app.processEvents()
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plt.autoRange()
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def fastPlot():
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## Different approach: generate a single item with all data points.
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## This runs about 20x faster.
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start = perf_counter()
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n = 15
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pts = 100
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x = np.linspace(0, 0.8, pts)
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y = np.random.random(size=pts)*0.8
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xdata = np.empty((n, n, pts))
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xdata[:] = x.reshape(1,1,pts) + np.arange(n).reshape(n,1,1)
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ydata = np.empty((n, n, pts))
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ydata[:] = y.reshape(1,1,pts) + np.arange(n).reshape(1,n,1)
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conn = np.ones((n*n,pts))
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conn[:,-1] = False # make sure plots are disconnected
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path = pg.arrayToQPath(xdata.flatten(), ydata.flatten(), conn.flatten())
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item = QtGui.QGraphicsPathItem(path)
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item.setPen(pg.mkPen('w'))
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plt.addItem(item)
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dt = perf_counter() - start
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print("Create plots took: %0.3fms" % (dt*1000))
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## Plot and clear 5 times, printing the time it took
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if hasattr(pg, 'arrayToQPath'):
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for i in range(5):
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plt.clear()
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fastPlot()
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app.processEvents()
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else:
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print("Skipping fast tests--arrayToQPath function is missing.")
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plt.autoRange()
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if __name__ == '__main__':
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pg.exec()
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