Matplotlib / python clickable points

To expand on what @tcaswell said, see the documentation here: http://matplotlib.org/users/event_handling.html

However, you might find a quick demo of pick events useful:

import matplotlib.pyplot as plt

def on_pick(event):
    artist = event.artist
    xmouse, ymouse = event.mouseevent.xdata, event.mouseevent.ydata
    x, y = artist.get_xdata(), artist.get_ydata()
    ind = event.ind
    print 'Artist picked:', event.artist
    print '{} vertices picked'.format(len(ind))
    print 'Pick between vertices {} and {}'.format(min(ind), max(ind)+1)
    print 'x, y of mouse: {:.2f},{:.2f}'.format(xmouse, ymouse)
    print 'Data point:', x[ind[0]], y[ind[0]]
    print

fig, ax = plt.subplots()

tolerance = 10 # points
ax.plot(range(10), 'ro-', picker=tolerance)

fig.canvas.callbacks.connect('pick_event', on_pick)

plt.show()

Exactly how you approach this will depend on what artist you’re using (In other words, did you use ax.plot vs. ax.scatter vs. ax.imshow?).

Pick events will have different attributes depending on the artist selected. There will always be event.artist and event.mouseevent. Most artists that have individual elements (e.g. Line2Ds, Collections, etc) will have a list of the index of the items selected as event.ind.

If you’d like to draw a polygon and select points inside, see: http://matplotlib.org/examples/event_handling/lasso_demo.html#event-handling-example-code-lasso-demo-py