.. _old_animation-dynamic_collection:

old_animation example code: dynamic_collection.py
=================================================

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

::

    import random
    from matplotlib.collections import RegularPolyCollection
    import matplotlib.cm as cm
    from matplotlib.pyplot import figure, show
    from numpy.random import rand
    
    fig = figure()
    ax = fig.add_subplot(111, xlim=(0,1), ylim=(0,1), autoscale_on=False)
    ax.set_title("Press 'a' to add a point, 'd' to delete one")
    # a single point
    offsets = [(0.5,0.5)]
    facecolors = [cm.jet(0.5)]
    
    collection = RegularPolyCollection(
        #fig.dpi,
        5, # a pentagon
        rotation=0,
        sizes=(50,),
        facecolors = facecolors,
        edgecolors = 'black',
        linewidths = (1,),
        offsets = offsets,
        transOffset = ax.transData,
        )
    
    ax.add_collection(collection)
    
    def onpress(event):
        """
        press 'a' to add a random point from the collection, 'd' to delete one
        """
        if event.key=='a':
            x,y = rand(2)
            color = cm.jet(rand())
            offsets.append((x,y))
            facecolors.append(color)
            collection.set_offsets(offsets)
            collection.set_facecolors(facecolors)
            fig.canvas.draw()
        elif event.key=='d':
            N = len(offsets)
            if N>0:
                ind = random.randint(0,N-1)
                offsets.pop(ind)
                facecolors.pop(ind)
                collection.set_offsets(offsets)
                collection.set_facecolors(facecolors)
                fig.canvas.draw()
    
    fig.canvas.mpl_connect('key_press_event', onpress)
    
    show()
    

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