Possible new version of the event handling resample.py

modified_resample.py

import numpy as np
import matplotlib.pyplot as plt


# A class that will downsample the data if there are too many points to display
class DataDisplayResampler(object):
    def __init__(self, xdata, ydata, max_disp_samples=80):
        self.origYData = ydata
        self.origXData = xdata
        self.max_disp_samples = max_disp_samples
        self.delta = xdata[-1] - xdata[0]

    def resample(self, xstart, xend):
        mask = (self.origXData > xstart) & (self.origXData < xend)
        xdata = self.origXData[mask]
        ydata = self.origYData[mask]
        downsampled = False  # Convenience flag to set a responsive title

        if len(xdata) > self.max_disp_samples:
            # Very simple downsampling that takes the points within
            # the range and picks every Nth point according to the
            # downsampling ratio.
            ds_ratio = len(xdata) // max(1, (self.max_disp_samples // 2))
            xdata = xdata[::ds_ratio]
            ydata = ydata[::ds_ratio]
            downsampled = True

        return xdata, ydata, downsampled

    def update(self, ax):
        # Update the line
        lims = ax.viewLim
        if np.abs(lims.width - self.delta) > 1e-8:
            self.delta = lims.width
            xx, yy, dsed = self.resample(*lims.intervalx)
            self.line.set_data(xx, yy)
            ax.set_title("Downsampled display" if dsed else "Full display")
            ax.figure.canvas.draw_idle()

# Create a signal
xdata = np.linspace(16, 365, (365-16))
ydata = np.sin(2*np.pi*xdata/153) + np.cos(2*np.pi*xdata/127)

d = DataDisplayResampler(xdata, ydata)

fig, ax = plt.subplots()

# Hook up the line
d.line, = ax.plot(xdata, ydata, 'o-', ms=5)
d.update(ax)  #  Downsample the original view if needed
ax.set_autoscale_on(False)  # Otherwise, infinite loop

# Connect for changing the view limits
ax.callbacks.connect('xlim_changed', d.update)

plt.show()