IPython Notebook widgets for Matplotlib interactivity

Question

I would like to use the ipython notebook widgets to add some degree of interactivity to inline matplotlib plots.

In general the plot can be quite heavy and I want to on

Answer 1

The solution turns out to be really simple. To avoid showing the first figure we just need to add a close() call before the interact call.

Recalling the example of the question, a cell like this will correctly show a single interactive figure (instead of two):

fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
plt.close(fig)

vline = ax.axvline(1)
hline = ax.axhline(0.5)

def set_cursor(x, y):
    vline.set_xdata((x, x))
    hline.set_ydata((y, y))
    display(fig)

interact(set_cursor, x=(1, 9, 0.01), y=(0, 5, 0.01))

A cleaner approach is defining the function add_cursor (in a separate cell or script):

def add_cursor(fig, ax):
    plt.close(fig)

    vline = ax.axvline(1, color='k')
    hline = ax.axhline(0.5, color='k')

    def set_cursor(x, y):
        vline.set_xdata((x, x))
        hline.set_ydata((y, y))
        display(fig)

    interact(set_cursor, x=ax.get_xlim(), y=ax.get_ylim())

and then call it whenever we want to add an interactive cursor:

fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
add_cursor(fig, ax)