Change dynamically the contents of a matplotlib plot.

Question

I while ago, I was comparing the output of two functions using python and matplotlib. The result was as good as simple, since plotting with matplotlib is quite easy: I just plotted two arrays with different markers. Piece of cake.

Now I find myself with the same problem, but now I have a lot of pair of curves to compare. I initially tried plotting everything with different colors and markers. This did not satisfy me since the ranges of each curve are not quite the same. In addition to this, I quickly ran out of colors and markers that were sufficiently different to identify (RGBCMYK, after that, custom colors resemble any of the previous ones).

I also tried subplotting each pair of curves, obtaining a window with many plots. Too crowded. I tried one window per plot, too many windows.

So I was just wondering if there is any existing widget or if you have any suggestion (or a different idea) to accomplish this:

I want to see a pair of curves and then select easily the next one, with a slidebar, button, mouse scroll, or any other widget or event. By changing curves, the previous one should disappear, the legend should change and its axis as well.

Answer 1

Well I managed to do it with an event handler for mouse clicks. I will change it for something more useful, but I post my solution anyway.

import matplotlib.pyplot as plt

figure = plt.figure()
# plotting
plt.plot([1,2,3],[10,20,30],'bo-')
plt.grid()
plt.legend()

def on_press(event):
    print 'you pressed', event.button, event.xdata, event.ydata
    event.canvas.figure.clear()
    # select new curves to plot, in this example [1,2,3] [0,0,0]
    event.canvas.figure.gca().plot([1,2,3],[0,0,0], 'ro-')
    event.canvas.figure.gca().grid()
    event.canvas.figure.gca().legend()
    event.canvas.draw()


figure.canvas.mpl_connect('button_press_event', on_press)

Answer 2

Sounds like you want to embed matplotlib in an application. There are some resources available for that:

• user interface examples
• Embedding in WX

Answer 3

I really like using traits. If you follow the tutorial Writing a graphical application for scientific programming , you should be able to do what you want. The tutorial shows how to interact with a matplotlib graph using graphical user interface.