zoomingmatplotlib

Matplotlib/Pyplot: How to zoom subplots together?


I have plots of 3-axis accelerometer time-series data (t,x,y,z) in separate subplots I'd like to zoom together. That is, when I use the "Zoom to Rectangle" tool on one plot, when I release the mouse all 3 plots zoom together.

Previously, I simply plotted all 3 axes on a single plot using different colors. But this is useful only with small amounts of data: I have over 2 million data points, so the last axis plotted obscures the other two. Hence the need for separate subplots.

I know I can capture matplotlib/pyplot mouse events (http://matplotlib.sourceforge.net/users/event_handling.html), and I know I can catch other events (http://matplotlib.sourceforge.net/api/backend_bases_api.html#matplotlib.backend_bases.ResizeEvent), but I don't know how to tell what zoom has been requested on any one subplot, and how to replicate it on the other two subplots.

I suspect I have the all the pieces, and need only that one last precious clue...

-BobC


Solution

  • The easiest way to do this is by using the sharex and/or sharey keywords when creating the axes:

    from matplotlib import pyplot as plt
    
    ax1 = plt.subplot(2,1,1)
    ax1.plot(...)
    ax2 = plt.subplot(2,1,2, sharex=ax1)
    ax2.plot(...)