Matplotlib plot zooming with scroll wheel

Question

Is it possible to bind the scroll wheel to zoom in/out when the cursor is hovering over a matplotlib plot?

Answer 1

This should work. It re-centers the graph on the location of the pointer when you scroll.

import matplotlib.pyplot as plt   def zoom_factory(ax,base_scale = 2.):     def zoom_fun(event):         # get the current x and y limits         cur_xlim = ax.get_xlim()         cur_ylim = ax.get_ylim()         cur_xrange = (cur_xlim[1] - cur_xlim[0])*.5         cur_yrange = (cur_ylim[1] - cur_ylim[0])*.5         xdata = event.xdata # get event x location         ydata = event.ydata # get event y location         if event.button == 'up':             # deal with zoom in             scale_factor = 1/base_scale         elif event.button == 'down':             # deal with zoom out             scale_factor = base_scale         else:             # deal with something that should never happen             scale_factor = 1             print event.button         # set new limits         ax.set_xlim([xdata - cur_xrange*scale_factor,                      xdata + cur_xrange*scale_factor])         ax.set_ylim([ydata - cur_yrange*scale_factor,                      ydata + cur_yrange*scale_factor])         plt.draw() # force re-draw      fig = ax.get_figure() # get the figure of interest     # attach the call back     fig.canvas.mpl_connect('scroll_event',zoom_fun)      #return the function     return zoom_fun 

Assuming you have an axis object ax

 ax.plot(range(10))  scale = 1.5  f = zoom_factory(ax,base_scale = scale) 

The optional argument base_scale allows you to set the scale factor to be what ever you want.

make sure you keep a copy of f around. The call back uses a weak-ref so if you do not keep a copy of f it might be garbage collected.

After writing this answer I decided this actually quite useful and put it in a gist