

.. _sphx_glr_gallery_pylab_examples_ginput_manual_clabel_sgskip.py:


=====================
Interactive functions
=====================

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




.. code-block:: python


    from __future__ import print_function

    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



.. code-block:: python


    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



.. code-block:: python


    # 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



.. code-block:: python


    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()

**Total running time of the script:** ( 0 minutes  0.000 seconds)



.. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: ginput_manual_clabel_sgskip.py <ginput_manual_clabel_sgskip.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: ginput_manual_clabel_sgskip.ipynb <ginput_manual_clabel_sgskip.ipynb>`

.. rst-class:: sphx-glr-signature

    `Generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_
