pyqtgraph/examples/multiplePlotSpeedTest.py
Ogi Moore d396d33799
Remove the use of pyqtgraph.ptime (#1914)
* Remove the use of pyqtgraph.ptime

With us supporting python3.7+, we have no more need for the ptime module
and can instead safely use perf_counter for everything.

* Address small issues PR turned up

* Reword comment in ImageView
2021-07-22 20:57:50 -07:00

92 lines
2.5 KiB
Python

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