.. _event_handling-data_browser:

event_handling example code: data_browser.py
============================================

[`source code <data_browser.py>`_]

::

    import numpy as np
    from pylab import figure, show
    
    
    X = np.random.rand(100, 200)
    xs = np.mean(X, axis=1)
    ys = np.std(X, axis=1)
    
    fig = figure()
    ax = fig.add_subplot(211)
    ax.set_title('click on point to plot time series')
    line, = ax.plot(xs, ys, 'o', picker=5)  # 5 points tolerance
    ax2 = fig.add_subplot(212)
    
    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 pervious 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)
            self.update()
    
        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
           self.update()
    
        def update(self):
            if self.lastind is None: return
    
            dataind = self.lastind
    
            ax2.cla()
            ax2.plot(X[dataind])
    
            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_visible(True)
            self.selected.set_data(xs[dataind], ys[dataind])
    
            self.text.set_text('selected: %d'%dataind)
            fig.canvas.draw()
    
    
    browser = PointBrowser()
    
    fig.canvas.mpl_connect('pick_event', browser.onpick)
    fig.canvas.mpl_connect('key_press_event', browser.onpress)
    
    show()
    

Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)