Changing Fonts for Graphs in R

UPDATE 2020 This can now be solved by using the ggtext package, e.g.:

install.packages(ggtext)

plot <- plot + theme(
  legend.text = ggtext::element_markdown(family = 'Times', face='bold')
)

In addition, you can use markdown to complement your plot text. I experienced ggtext simpler and more fail safe than extrafont.

Here's a ggplot solution using WindowsFonts(...)

windowsFonts(Times=windowsFont("Times New Roman"))
library(ggplot2)
ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme_bw() +
  theme(text=element_text(family="Times", face="bold", size=12)) #Times New Roman, 12pt, Bold

As you can see, the text really is Times New Roman.

The main idea is that whatever name you give the font internally in R, using

windowsFonts(name=windowsFont("system name"))

you should use to reference the font in

theme(text=element_text(family="name",...),...)

You can change the font in Windows to Times New Roman using the windowsFonts() command and the family option in plot:

x = seq(1,10,1)
y = 1.5*x
windowsFonts(A = windowsFont("Times New Roman"))
plot(x, y,
  family="A",
  main = "title",
  font=2)

Bold text comes from font=2. As for the size, see ?cex(). Also, see here: http://www.statmethods.net/advgraphs/parameters.html

You can use the extrafont package.

install.packages("extrafont")
library(extrafont)
font_import()
loadfonts(device="win")       #Register fonts for Windows bitmap output
fonts()                       #vector of font family names
##  [1] "Andale Mono"                  "AppleMyungjo"                
##  [3] "Arial Black"                  "Arial"                       
##  [5] "Arial Narrow"                 "Arial Rounded MT Bold"  

library(ggplot2)
data(mtcars)
ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +     
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme_bw() +
  theme(text=element_text(family="Times New Roman", face="bold", size=12)) #Times New Roman, 12pt, Bold
#example taken from the Github project page

Note: Using the extrafont package, you can also embed these fonts in PDF and EPS files (make plots in R and export to PDF/EPS). You can also directly create math symbols (see math equation in plot below), usually created using TeX. More information here and here. Also look at the github project page.

Also look at this answer which describes creating xkcd style graphs using the extrafont package.