matplotlib set yaxis label size

Question

How can I change the size of only the yaxis label? Right now, I change the size of all labels using

pylab.rc('font', family='serif', size=40)

but in my case, I would like to make the y-axis label larger than the x-axis. However, I'd like to leave the tick labels alone.

I've tried, for example:

pylab.gca().get_ylabel().set_fontsize(60)

but I only get:

AttributeError: 'str' object has no attribute 'set_fontsize'

So, obviously that doesn't work. I've seen lots of stuff for tick sizes, but nothing for the axis labels themselves.

Solution

If you are using the 'pylab' for interactive plotting you can set the labelsize at creation time with pylab.ylabel('Example', fontsize=40).

If you use pyplot programmatically you can either set the fontsize on creation with ax.set_ylabel('Example', fontsize=40) or afterwards with ax.yaxis.label.set_size(40).