How to rotate the axis labels in ggplot2?

Question

I have the following graph that I generated using ggplot2

I had finalPlo

Answer 1

For the rotation angle of the axis text you need to use element_text(). See this post on SO for some examples. For spacing over two lines I would add a "\n" on the location in the string where you want to put the newline.

This will set the correct orientation for the y axis text and force a line break:

finalPlot + ylab("Number of\nSolutions") + 
    theme(axis.title.y = element_text(angle = 0))

Answer 2

The syntax has changed in recent versions of ggplot2; if you try the above answer, you'll get

Error: Use 'theme' instead. (Defunct; last used in version 0.9.1)

These days you should use

finalPlot + ylab("Number of\nSolutions") + theme(axis.title.y = element_text(angle=0))