How to pass ggplot2 themes

Question

I have an older ggplot2 book and it is outdated. It mentions using qplot, and opts.

I am trying to learn how to setup a ggplot2 graph correctly. I would like to know if my following code is the "correct" or "accepted" way of doing things.

I would like to pass themes to a plot, like title, axis titles, grid lines, colors of plot window, etc...

Currently this code block works until I attempt to pass a theme where I change the title. Here is the code, and a picture of the graph it makes before I pass the theme

brooks.sr <- ggplot(data=sim_dat, aes(x=rates, y=means))
brooks.sr.line <-  brooks.sr + geom_line(data=sim_dat[sim_dat$stream=="Brooks", ]) + 
geom_hline(aes(yintercept=.944), colour = "red")

then I try to add this line of code

brooks.sr.line + theme(title = element_text("Mean LWD Density across Sampling Rates"))

And i get this error

> brooks.sr.line + theme(title = element_text("Mean LWD Density across    Sampling Rates"))
Warning messages:
1: In grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  :
  font family not found in Windows font database
2: In grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  :
  font family not found in Windows font database
3: In grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  :
  font family not found in Windows font database
4: In grid.Call.graphics(L_text, as.graphicsAnnot(x$label), x$x, x$y,  :
  font family not found in Windows font database
5: In grid.Call.graphics(L_text, as.graphicsAnnot(x$label), x$x, x$y,  :
  font family not found in Windows font database

I know have the following code block, which seems better, and I have added a title and line. But, I can not find out how to change the Axis titles, I can see where you can pass the theme and element to modify the text of the title, but not change the title itself

speelyai.sr <- ggplot(data=sim_dat, aes(x=rates, y=means))
speelyai.sr.line <-  speelyai.sr +   
geom_line(data=sim_dat[sim_dat$stream=="Speelyai", ]) + 
geom_hline(aes(yintercept=.584), colour = "red");speelyai.sr.line
speelyai.sr.line + ggtitle("Mean LWD Density using Simple Random 
 Sampling\nunder different Sampling Efforts") +
               theme(plot.title=element_text(size=rel(1.5), family="Times", face="bold"))

Thanks for any help

theme is used to control the appearance, while the content has to be set with other functions, e..g ggtitle() for the title text, labs() for the axis titles, etc. — baptiste

Docconcoct Docconcoct · Accepted Answer · 2015-08-05T22:15:12

This should work for titling the plot:

+ labs(title = expression("Mean LWD Density across Sampling Rates"))

You can also label the y and x-axes from the same line of code:

+ labs(x="X-Title", y="Y-Title", title = expression("Mean LWD Density across Sampling Rates"))

How to pass ggplot2 themes

1 Answers