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event_handling example code: data_browser.pyΒΆ

[source code]

import numpy as np

class PointBrowser:
    Click on a point to select and highlight it -- the data that
    generated the point will be shown in the lower axes.  Use the 'n'
    and 'p' keys to browse through the next and previous points
    def __init__(self):
        self.lastind = 0

        self.text = ax.text(0.05, 0.95, 'selected: none',
                            transform=ax.transAxes, va='top')
        self.selected,  = ax.plot([xs[0]], [ys[0]], 'o', ms=12, alpha=0.4,
                                  color='yellow', visible=False)

    def onpress(self, event):
        if self.lastind is None: return
        if event.key not in ('n', 'p'): return
        if event.key=='n': inc = 1
        else:  inc = -1

        self.lastind += inc
        self.lastind = np.clip(self.lastind, 0, len(xs)-1)

    def onpick(self, event):

       if event.artist!=line: return True

       N = len(event.ind)
       if not N: return True

       # the click locations
       x = event.mouseevent.xdata
       y = event.mouseevent.ydata

       distances = np.hypot(x-xs[event.ind], y-ys[event.ind])
       indmin = distances.argmin()
       dataind = event.ind[indmin]

       self.lastind = dataind

    def update(self):
        if self.lastind is None: return

        dataind = self.lastind


        ax2.text(0.05, 0.9, 'mu=%1.3f\nsigma=%1.3f'%(xs[dataind], ys[dataind]),
                 transform=ax2.transAxes, va='top')
        ax2.set_ylim(-0.5, 1.5)
        self.selected.set_data(xs[dataind], ys[dataind])

        self.text.set_text('selected: %d'%dataind)

if __name__ == '__main__':
    import matplotlib.pyplot as plt

    X = np.random.rand(100, 200)
    xs = np.mean(X, axis=1)
    ys = np.std(X, axis=1)

    fig, (ax, ax2) = plt.subplots(2, 1)
    ax.set_title('click on point to plot time series')
    line, = ax.plot(xs, ys, 'o', picker=5)  # 5 points tolerance

    browser = PointBrowser()

    fig.canvas.mpl_connect('pick_event', browser.onpick)
    fig.canvas.mpl_connect('key_press_event', browser.onpress)

Keywords: python, matplotlib, pylab, example, codex (see Search examples)