.. _api-colorbar_basics:

api example code: colorbar_basics.py
====================================



.. plot:: /home/tcaswell/src/p/matplotlib/doc/mpl_examples/api/colorbar_basics.py

::

    """
    ========
    Colorbar
    ========
    
    This example shows how to use colorbar by specifying the mappable object (here
    the imshow returned object) and the axes to attach the colorbar to.
    """
    
    import numpy as np
    import matplotlib.pyplot as plt
    
    # setup some generic data
    N = 37
    x, y = np.mgrid[:N, :N]
    Z = (np.cos(x*0.2) + np.sin(y*0.3))
    
    # mask out the negative and positve values, respectively
    Zpos = np.ma.masked_less(Z, 0)
    Zneg = np.ma.masked_greater(Z, 0)
    
    fig, (ax1, ax2) = plt.subplots(figsize=(8, 3), ncols=2)
    
    # plot just the positive data and save the
    # color "mappable" object returned by ax1.imshow
    pos = ax1.imshow(Zpos, cmap='Blues', interpolation='none')
    
    # add the colorbar using the figure's method,
    # telling which mappable we're talking about and
    # which axes object it should be near
    fig.colorbar(pos, ax=ax1)
    
    # repeat everything above for the the negative data
    neg = ax2.imshow(Zneg, cmap='Reds_r', interpolation='none')
    fig.colorbar(neg, ax=ax2)
    
    plt.show()
    

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