.. _animation-strip_chart_demo:

animation example code: strip_chart_demo.py
===========================================

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

::

    """
    ============
    Oscilloscope
    ============
    
    Emulates an oscilloscope.
    """
    import numpy as np
    from matplotlib.lines import Line2D
    import matplotlib.pyplot as plt
    import matplotlib.animation as animation
    
    
    class Scope(object):
        def __init__(self, ax, maxt=2, dt=0.02):
            self.ax = ax
            self.dt = dt
            self.maxt = maxt
            self.tdata = [0]
            self.ydata = [0]
            self.line = Line2D(self.tdata, self.ydata)
            self.ax.add_line(self.line)
            self.ax.set_ylim(-.1, 1.1)
            self.ax.set_xlim(0, self.maxt)
    
        def update(self, y):
            lastt = self.tdata[-1]
            if lastt > self.tdata[0] + self.maxt:  # reset the arrays
                self.tdata = [self.tdata[-1]]
                self.ydata = [self.ydata[-1]]
                self.ax.set_xlim(self.tdata[0], self.tdata[0] + self.maxt)
                self.ax.figure.canvas.draw()
    
            t = self.tdata[-1] + self.dt
            self.tdata.append(t)
            self.ydata.append(y)
            self.line.set_data(self.tdata, self.ydata)
            return self.line,
    
    
    def emitter(p=0.03):
        'return a random value with probability p, else 0'
        while True:
            v = np.random.rand(1)
            if v > p:
                yield 0.
            else:
                yield np.random.rand(1)
    
    fig, ax = plt.subplots()
    scope = Scope(ax)
    
    # pass a generator in "emitter" to produce data for the update func
    ani = animation.FuncAnimation(fig, scope.update, emitter, interval=10,
                                  blit=True)
    
    
    plt.show()
    

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