Plotting two graphs that share an x-axis in matplotlib

Question

I have to plot 2 graphs in a single screen. The x-axis remains the same but the y-axis should be different.

How can I do that in 'matplotlib'?

Answer 1

twinx is the function you're looking for; here's an example of how to use it.

Answer 2

subplot will let you plot more than one figure on the same canvas. See the example on the linked documentation page.

There is an example of a shared axis plot in the examples directory, called shared_axis_demo.py :

from pylab import *

t = arange(0.01, 5.0, 0.01)
s1 = sin(2*pi*t)
s2 = exp(-t)
s3 = sin(4*pi*t)
ax1 = subplot(311)
plot(t,s1)
setp( ax1.get_xticklabels(), fontsize=6)

## share x only
ax2 = subplot(312, sharex=ax1)
plot(t, s2)
# make these tick labels invisible
setp( ax2.get_xticklabels(), visible=False)

# share x and y
ax3 = subplot(313,  sharex=ax1, sharey=ax1)
plot(t, s3)
xlim(0.01,5.0)
show()