.. _event_handling-resample: event_handling example code: resample.py ======================================== [`source code `_] :: import numpy as np import matplotlib.pyplot as plt from scikits.audiolab import wavread # A class that will downsample the data and recompute when zoomed. class DataDisplayDownsampler(object): def __init__(self, xdata, ydata): self.origYData = ydata self.origXData = xdata self.numpts = 3000 self.delta = xdata[-1] - xdata[0] def resample(self, xstart, xend): # Very simple downsampling that takes the points within the range # and picks every Nth point mask = (self.origXData > xstart) & (self.origXData < xend) xdata = self.origXData[mask] ratio = int(xdata.size / self.numpts) + 1 xdata = xdata[::ratio] ydata = self.origYData[mask] ydata = ydata[::ratio] return xdata, ydata def update(self, ax): # Update the line lims = ax.viewLim if np.abs(lims.width - self.delta) > 1e-8: self.delta = lims.width xstart, xend = lims.intervalx self.line.set_data(*self.downsample(xstart, xend)) ax.figure.canvas.draw_idle() # Read data data = wavread('/usr/share/sounds/purple/receive.wav')[0] ydata = np.tile(data[:, 0], 100) xdata = np.arange(ydata.size) d = DataDisplayDownsampler(xdata, ydata) fig, ax = plt.subplots() #Hook up the line xdata, ydata = d.downsample(xdata[0], xdata[-1]) d.line, = ax.plot(xdata, ydata) ax.set_autoscale_on(False) # Otherwise, infinite loop # Connect for changing the view limits ax.callbacks.connect('xlim_changed', d.update) plt.show() Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)