.. _pylab_examples-ginput_manual_clabel:

pylab_examples example code: ginput_manual_clabel.py
====================================================

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

::

    # -*- noplot -*-
    
    from __future__ import print_function
    """
    This provides examples of uses of interactive functions, such as ginput,
    waitforbuttonpress and manual clabel placement.
    
    This script must be run interactively using a backend that has a
    graphical user interface (for example, using GTKAgg backend, but not
    PS backend).
    
    See also ginput_demo.py
    """
    import time
    import matplotlib
    import numpy as np
    import matplotlib.cm as cm
    import matplotlib.mlab as mlab
    import matplotlib.pyplot as plt
    
    
    def tellme(s):
        print(s)
        plt.title(s, fontsize=16)
        plt.draw()
    
    ##################################################
    # Define a triangle by clicking three points
    ##################################################
    plt.clf()
    plt.axis([-1., 1., -1., 1.])
    plt.setp(plt.gca(), autoscale_on=False)
    
    tellme('You will define a triangle, click to begin')
    
    plt.waitforbuttonpress()
    
    happy = False
    while not happy:
        pts = []
        while len(pts) < 3:
            tellme('Select 3 corners with mouse')
            pts = np.asarray(plt.ginput(3, timeout=-1))
            if len(pts) < 3:
                tellme('Too few points, starting over')
                time.sleep(1)  # Wait a second
    
        ph = plt.fill(pts[:, 0], pts[:, 1], 'r', lw=2)
    
        tellme('Happy? Key click for yes, mouse click for no')
    
        happy = plt.waitforbuttonpress()
    
        # Get rid of fill
        if not happy:
            for p in ph:
                p.remove()
    
    ##################################################
    # Now contour according to distance from triangle
    # corners - just an example
    ##################################################
    
    
    # Define a nice function of distance from individual pts
    def f(x, y, pts):
        z = np.zeros_like(x)
        for p in pts:
            z = z + 1/(np.sqrt((x - p[0])**2 + (y - p[1])**2))
        return 1/z
    
    X, Y = np.meshgrid(np.linspace(-1, 1, 51), np.linspace(-1, 1, 51))
    Z = f(X, Y, pts)
    
    CS = plt.contour(X, Y, Z, 20)
    
    tellme('Use mouse to select contour label locations, middle button to finish')
    CL = plt.clabel(CS, manual=True)
    
    ##################################################
    # Now do a zoom
    ##################################################
    tellme('Now do a nested zoom, click to begin')
    plt.waitforbuttonpress()
    
    happy = False
    while not happy:
        tellme('Select two corners of zoom, middle mouse button to finish')
        pts = np.asarray(plt.ginput(2, timeout=-1))
    
        happy = len(pts) < 2
        if happy:
            break
    
        pts = np.sort(pts, axis=0)
        plt.axis(pts.T.ravel())
    
    tellme('All Done!')
    plt.show()
    

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