.. _images_contours_and_fields-streamplot_demo_features:

images_contours_and_fields example code: streamplot_demo_features.py
====================================================================



.. plot:: /home/tcaswell/source/p/matplotlib/doc/mpl_examples/images_contours_and_fields/streamplot_demo_features.py

::

    """
    Demo of the `streamplot` function.
    
    A streamplot, or streamline plot, is used to display 2D vector fields. This
    example shows a few features of the stream plot function:
    
        * Varying the color along a streamline.
        * Varying the density of streamlines.
        * Varying the line width along a stream line.
    """
    import numpy as np
    import matplotlib.pyplot as plt
    
    Y, X = np.mgrid[-3:3:100j, -3:3:100j]
    U = -1 - X**2 + Y
    V = 1 + X - Y**2
    speed = np.sqrt(U*U + V*V)
    
    fig0, ax0 = plt.subplots()
    strm = ax0.streamplot(X, Y, U, V, color=U, linewidth=2, cmap=plt.cm.autumn)
    fig0.colorbar(strm.lines)
    
    fig1, (ax1, ax2) = plt.subplots(ncols=2)
    ax1.streamplot(X, Y, U, V, density=[0.5, 1])
    
    lw = 5*speed / speed.max()
    ax2.streamplot(X, Y, U, V, density=0.6, color='k', linewidth=lw)
    
    plt.show()
    

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