diff --git a/examples/__main__.py b/examples/__main__.py index 6c2e8b97..ea948bf4 100644 --- a/examples/__main__.py +++ b/examples/__main__.py @@ -31,6 +31,7 @@ examples = OrderedDict([ ('Histograms', 'histogram.py'), ('Auto-range', 'PlotAutoRange.py'), ('Remote Plotting', 'RemoteSpeedTest.py'), + ('Scrolling plots', 'scrollingPlots.py'), ('HDF5 big data', 'hdf5.py'), ('Demos', OrderedDict([ ('Optics', 'optics_demos.py'), diff --git a/examples/scrollingPlots.py b/examples/scrollingPlots.py new file mode 100644 index 00000000..623b9ab1 --- /dev/null +++ b/examples/scrollingPlots.py @@ -0,0 +1,118 @@ +# -*- coding: utf-8 -*- +""" +Various methods of drawing scrolling plots. +""" +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 + +win = pg.GraphicsWindow() +win.setWindowTitle('pyqtgraph example: Scrolling Plots') + + +# 1) Simplest approach -- update data in the array such that plot appears to scroll +# In these examples, the array size is fixed. +p1 = win.addPlot() +p2 = win.addPlot() +data1 = np.random.normal(size=300) +curve1 = p1.plot(data1) +curve2 = p2.plot(data1) +ptr1 = 0 +def update1(): + global data1, curve1, ptr1 + data1[:-1] = data1[1:] # shift data in the array one sample left + # (see also: np.roll) + data1[-1] = np.random.normal() + curve1.setData(data1) + + ptr1 += 1 + curve2.setData(data1) + curve2.setPos(ptr1, 0) + + +# 2) Allow data to accumulate. In these examples, the array doubles in length +# whenever it is full. +win.nextRow() +p3 = win.addPlot() +p4 = win.addPlot() +# Use automatic downsampling and clipping to reduce the drawing load +p3.setDownsampling(mode='peak') +p4.setDownsampling(mode='peak') +p3.setClipToView(True) +p4.setClipToView(True) +p3.setRange(xRange=[-100, 0]) +p3.setLimits(xMax=0) +curve3 = p3.plot() +curve4 = p4.plot() + +data3 = np.empty(100) +ptr3 = 0 + +def update2(): + global data3, ptr3 + data3[ptr3] = np.random.normal() + ptr3 += 1 + if ptr3 >= data3.shape[0]: + tmp = data3 + data3 = np.empty(data3.shape[0] * 2) + data3[:tmp.shape[0]] = tmp + curve3.setData(data3[:ptr3]) + curve3.setPos(-ptr3, 0) + curve4.setData(data3[:ptr3]) + + +# 3) Plot in chunks, adding one new plot curve for every 100 samples +chunkSize = 100 +# Remove chunks after we have 10 +maxChunks = 10 +startTime = pg.ptime.time() +win.nextRow() +p5 = win.addPlot(colspan=2) +p5.setLabel('bottom', 'Time', 's') +p5.setXRange(-10, 0) +curves = [] +data5 = np.empty((chunkSize+1,2)) +ptr5 = 0 + +def update3(): + global p5, data5, ptr5, curves + now = pg.ptime.time() + for c in curves: + c.setPos(-(now-startTime), 0) + + i = ptr5 % chunkSize + if i == 0: + curve = p5.plot() + curves.append(curve) + last = data5[-1] + data5 = np.empty((chunkSize+1,2)) + data5[0] = last + while len(curves) > maxChunks: + c = curves.pop(0) + p5.removeItem(c) + else: + curve = curves[-1] + data5[i+1,0] = now - startTime + data5[i+1,1] = np.random.normal() + curve.setData(x=data5[:i+2, 0], y=data5[:i+2, 1]) + ptr5 += 1 + + +# update all plots +def update(): + update1() + update2() + update3() +timer = pg.QtCore.QTimer() +timer.timeout.connect(update) +timer.start(50) + + + +## Start Qt event loop unless running in interactive mode or using pyside. +if __name__ == '__main__': + import sys + if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'): + QtGui.QApplication.instance().exec_() diff --git a/pyqtgraph/graphicsItems/PlotDataItem.py b/pyqtgraph/graphicsItems/PlotDataItem.py index 3e760ce1..befc5783 100644 --- a/pyqtgraph/graphicsItems/PlotDataItem.py +++ b/pyqtgraph/graphicsItems/PlotDataItem.py @@ -546,7 +546,7 @@ class PlotDataItem(GraphicsObject): if view is None or not view.autoRangeEnabled()[0]: # this option presumes that x-values have uniform spacing range = self.viewRect() - if range is not None: + if range is not None and len(x) > 1: dx = float(x[-1]-x[0]) / (len(x)-1) # clip to visible region extended by downsampling value x0 = np.clip(int((range.left()-x[0])/dx)-1*ds , 0, len(x)-1)