Once upon a time, I changed my ggplot2 font using windowsFonts(Times=windowsFont("TT Times New Roman")). Now, I can't get it off of this.

In trying to set family="" in ggplot2 theme(), I can't seem to generate a change in fonts as I compile the MWE below with different font families.

library(ggplot2)
library(extrafont)
loadfonts(device = "win")

a <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
        ggtitle("Fuel Efficiency of 32 Cars") +
        xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
        theme(text=element_text(size=16, 
#       family="Comic Sans MS"))
#       family="CM Roman"))
#       family="TT Times New Roman"))
#       family="Sans"))
        family="Serif"))


print(a)
print("Graph should have refreshed")

R is returning a warning font family not found in Windows font database, but there was a tutorial I was following (if I can find it again I will update the link here) that said this was normal and not a problem. Also, somehow this worked at one point because my graph once used some arial or helvitica type font. I think this has always been a present warning even during the initial times migration.

UPDATE

when I run windowsFonts() my output is

$serif [1] "TT Times New Roman"

$sans [1] "TT Arial"

$mono [1] "TT Courier New"

But, this is after I ran font_import() so I can only conclude that my fonts are not being saved in the right place. The code that ran the font_import() request actually loads the libraries with:

LocalLibraryLocation <- paste0("C:\\Users\\",Sys.getenv("USERNAME"),"\\Documents","\\R\\win-library\\3.2");
    .libPaths(c(LocalLibraryLocation, .libPaths()))

You just missed an initialization step I think.

You can see what fonts you have available with the command windowsFonts(). For example mine looks like this when I started looking at this:

> windowsFonts()
$serif
[1] "TT Times New Roman"

$sans
[1] "TT Arial"

$mono
[1] "TT Courier New"

After intalling the package extraFont and running font_import like this (it took like 5 minutes):

library(extrafont)
font_import()
loadfonts(device = "win")

I had many more available - arguable too many, certainly too many to list here.

Then I tried your code:

library(ggplot2)
library(extrafont)
loadfonts(device = "win")

a <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme(text=element_text(size=16,  family="Comic Sans MS"))
print(a)

yielding this:

Update:

You can find the name of a font you need for the family parameter of element_text with the following code snippet:

> names(wf[wf=="TT Times New Roman"])
[1] "serif"

And then:

library(ggplot2)
library(extrafont)
loadfonts(device = "win")

a <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme(text=element_text(size=16,  family="serif"))
print(a)

yields: