from pylab import figure, show

# Create some data: one x, three different y
x = arange(0.0, 20.0, 0.01)
y1 = sin(2*pi*x)
y2 = exp(-x)
y3 = y1*y2

# Create a figure and add three subplots.
fig = figure()
ax1 = fig.add_subplot(311)
ax2 = fig.add_subplot(312, sharex=ax1)  # share ax1's xaxis
ax3 = fig.add_subplot(313, sharex=ax1)  # share ax1's xaxis

# Plot
ax1.plot(x,y1)
ax2.plot(x,y2)
ax3.plot(x,y3)

# Show the figure.
show()

Here’s a video of what the interaction is like with this figure (matplotlib automatically adds the pan, zoom, home, etc buttons to all figures):

Notice that the y-axis remained independent in each of the three subplots. As you’d expect, the add_subplot() method accepts a sharey keyword argument as well. You can even pass both sharex and sharey . . . this is most useful when two subplots show data with the same units.