Bar chart corruption when plotting multiple subplots in MATPLOTLIB
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I've created a class that allows a user to add several charts to a MATPLOTLIB window. These can be either a line chart or a bar chart. It also has the feature that when a chart has already been added to the window (as identified from rowID) rather than draw a new plot it will replace the data in the old plot. ie it allows for updates (animation)
This works grand for the line plot but I get corruption when plotting several bar charts. The class looks like: import math class TFrmPlot(): def __init__(self, point_lists, deleteCallback, plotType, rowID): import matplotlib matplotlib.interactive( True ) matplotlib.use( 'WXAgg' ) import matplotlib.pyplot as plt self.plt = plt self.fig = plt.figure() self.fig.canvas.mpl_connect('close_event', self.on_close) import matplotlib.axes as ax self.ax = ax self.deleteCallback = deleteCallback self.chartArray = [] self.addChart(point_lists, plotType, rowID) def close(self): self.plt.close('all') #self.fig.close() def replaceChartDataIfChartExists(self, point_lists, rowID): if rowID==0: pass for chart in self.chartArray: for plot in chart.plots: if plot.rowID == rowID: plot.points = point_lists if plot.plotType=="Point": plot.plotItem.set_data(point_lists[0],point_lists[1]) chart.subPlot.draw_artist(plot.plotItem) self.fig.canvas.blit(chart.subPlot.bbox) else: for rect, h in zip(plot.plotItem, point_lists[1]): rect.set_height(h) chart.subPlot.relim() chart.subPlot.autoscale_view(True,True,True) self.plt.draw() return True return False def addChart(self, point_lists, plotType, rowID): self.chartArray.append(TChart(rowID,plotType,point_lists)) self._drawAll() def addPlot(self, point_lists, plotType, rowID): chartNum = len(self.chartArray) self.chartArray[chartNum-1].plots.append(TPlot(rowID,plotType,point_lists)) self._drawAll() def on_close(self, event): self.deleteCallback() def _drawAll(self): self.plt.clf() numSubPlots = len(self.chartArray) numCols = self._noCols(numSubPlots) IndexConverter = TIndexConverter(numCols) subPlot = None for chartIndex in range(0,numSubPlots): if numSubPlots==1: subPlot = self.fig.add_subplot(1,1,1) elif numSubPlots==2: subPlot = self.fig.add_subplot(1,2,chartIndex+1) else: subPlot = self.fig.add_subplot(2,numCols,IndexConverter._getSubPlotIndex(chartIndex)) subPlot.relim() subPlot.autoscale_view(True,True,True) self.chartArray[chartIndex].subPlot = subPlot self._drawSubs(self.chartArray[chartIndex]) self.plt.show() def _drawSubs(self, chart): for plot in chart.plots: if plot.plotType=="Point": chart.subPlot.plot(plot.points[0],plot.points[1]) plot.plotItem = chart.subPlot.lines[len(chart.subPlot.lines)-1] else: kwargs = {"alpha":0.5} plot.plotItem = chart.subPlot.bar(plot.points[0],plot.points[1], width=self._calculateleastDiff(plot.points[0]), **kwargs) def _noCols(self, numSubPlots): return math.ceil(float(numSubPlots)/2.0) def _calculateleastDiff(self, xValues): xValues2 = sorted(xValues) leastDiff = None lastValue = None for value in xValues2: if lastValue is not None: diff = value-lastValue if leastDiff is None or diff < leastDiff: leastDiff = diff lastValue = value return leastDiff This is a bit long so to summarise: addChart -- basically adds a new subplot addPlot -- adds a new line or bar to an existing subplot replaceChartDataIfChartExists -- refreshes the data if the ID already exists The dummy data that I'm using just plots a positive gradient and a negative gradient line in succession. My plots however can get into a state where one/some or all of the bar plots become corrupted. It looks almost like the x/y axis has been rotated, with the individual bars not starting from the x-axis. The issue is intermittent; sometimes I will get several plots as expected. Once a plot becomes corrupted all future updates remain corrupted. Corrupted Chart: 
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