Slicing plots generated by ggplot2

I wonder if it's possible to slice a graph respectively a .png file generated with ggsave. If I do 开发者_StackOverflownot want to use the default legend ort title and set it to FALSE it leaves me with a lot of white space. So is there an R way to just cut the file several pixels above and below the graph itself?

Thx in advance!

You could change the plot.margin, e.g.

p + opts(plot.margin=unit(c(-1, 0, -1, 0), "lines"))

Since version 0.9.2 opts has been replaced by theme:

p + theme(plot.margin = unit(c(-1, 0, -1, -), "lines"))