# Writing Figures to a File

Initialize a plot that will be written directly to a file using `pdf`, `png`, etc. Within the function you will need to specify a name for your image, and the width and height (optional). Then create a plot using the usual functions in R. Finally, close the file using the `dev.off()` function. There are also `bmp`, `tiff`, and `jpeg` functions, though the `jpeg` function has proven less stable than the others.

```r
pdf("boxplot.pdf")
ggplot(data=df, aes(x= genotype, y=samplemeans, fill=celltype)) + 
  geom_boxplot() + 
  ggtitle('Genotype differences in average gene expression') +
  xlab('Genotype') +
  ylab('Mean expression') +
  theme(plot.title = element_text(size = rel(1.5)),
        axis.title = element_text(size = rel(1.5)),
        axis.text = element_text(size = rel(1.25)))
dev.off()
```