.. _pylab_examples-quadmesh_demo:

pylab_examples example code: quadmesh_demo.py
=============================================



.. plot:: /builddir/build/BUILD/matplotlib-1.2.0/doc/mpl_examples/pylab_examples/quadmesh_demo.py

::

    #!/usr/bin/env python
    """
    pcolormesh uses a QuadMesh, a faster generalization of pcolor, but
    with some restrictions.
    
    This demo illustrates a bug in quadmesh with masked data.
    """
    
    import numpy as np
    from matplotlib.pyplot import figure, show, savefig
    from matplotlib import cm, colors
    from numpy import ma
    
    n = 12
    x = np.linspace(-1.5,1.5,n)
    y = np.linspace(-1.5,1.5,n*2)
    X,Y = np.meshgrid(x,y);
    Qx = np.cos(Y) - np.cos(X)
    Qz = np.sin(Y) + np.sin(X)
    Qx = (Qx + 1.1)
    Z = np.sqrt(X**2 + Y**2)/5;
    Z = (Z - Z.min()) / (Z.max() - Z.min())
    
    # The color array can include masked values:
    Zm = ma.masked_where(np.fabs(Qz) < 0.5*np.amax(Qz), Z)
    
    
    fig = figure()
    ax = fig.add_subplot(121)
    ax.set_axis_bgcolor("#bdb76b")
    ax.pcolormesh(Qx,Qz,Z, shading='gouraud')
    ax.set_title('Without masked values')
    
    ax = fig.add_subplot(122)
    ax.set_axis_bgcolor("#bdb76b")
    #  You can control the color of the masked region:
    #cmap = cm.jet
    #cmap.set_bad('r', 1.0)
    #ax.pcolormesh(Qx,Qz,Zm, cmap=cmap)
    #  Or use the default, which is transparent:
    col = ax.pcolormesh(Qx,Qz,Zm,shading='gouraud')
    ax.set_title('With masked values')
    
    
    show()
    

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