How to change the font on a chart in R?

Question

I want to use the source Times New Roman on the chart, but the R/Rstudio returns an error message saying not to find it. Obviously the source is somewhere because I use MS Word, for example.

A while ago the command below worked normally and stopped working at some point after some update I do not know if it was the Windows, of R, of Rstudio or of ggplot2.

# Exemplo reproduzível a partir de um banco de dados 
# que já vem incluso com o ggplot2:

library(ggplot2)
ggplot(data = diamonds, aes(x = carat, y = price)) + 
  geom_point() + 
  labs(title = "Diamantes: Quilates X Preço") + 
  theme(plot.title = element_text(family = "Times New Roman"))

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in Windows font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in Windows font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in Windows font database

devtools::session_info()
#> Session info -------------------------------------------------------------
#>  setting  value                       
#>  version  R version 3.4.3 (2017-11-30)
#>  system   x86_64, mingw32             
#>  ui       RTerm                       
#>  language (EN)                        
#>  collate  Portuguese_Brazil.1252      
#>  tz       America/Sao_Paulo           
#>  date     2017-12-03
#> Packages -----------------------------------------------------------------
#>  package    * version date       source                         
#>  backports    1.1.1   2017-09-25 CRAN (R 3.4.1)                 
#>  base       * 3.4.3   2017-11-30 local                          
#>  colorspace   1.3-2   2016-12-14 CRAN (R 3.4.0)                 
#>  compiler     3.4.3   2017-11-30 local                          
#>  datasets   * 3.4.3   2017-11-30 local                          
#>  devtools     1.13.4  2017-11-09 CRAN (R 3.4.2)                 
#>  digest       0.6.12  2017-01-27 CRAN (R 3.4.0)                 
#>  evaluate     0.10.1  2017-06-24 CRAN (R 3.4.0)                 
#>  ggplot2    * 2.2.1   2016-12-30 CRAN (R 3.4.0)                 
#>  graphics   * 3.4.3   2017-11-30 local                          
#>  grDevices  * 3.4.3   2017-11-30 local                          
#>  grid         3.4.3   2017-11-30 local                          
#>  gtable       0.2.0   2016-02-26 CRAN (R 3.4.0)                 
#>  htmltools    0.3.6   2017-04-28 CRAN (R 3.4.0)                 
#>  knitr        1.17    2017-08-10 CRAN (R 3.4.1)                 
#>  labeling     0.3     2014-08-23 CRAN (R 3.4.0)                 
#>  lazyeval     0.2.1   2017-10-29 CRAN (R 3.4.2)                 
#>  magrittr     1.5     2014-11-22 CRAN (R 3.4.0)                 
#>  memoise      1.1.0   2017-12-01 Github (hadley/memoise@d63ae9c)
#>  methods    * 3.4.3   2017-11-30 local                          
#>  munsell      0.4.3   2016-02-13 CRAN (R 3.4.0)                 
#>  plyr         1.8.4   2016-06-08 CRAN (R 3.4.0)                 
#>  Rcpp         0.12.14 2017-11-23 CRAN (R 3.4.2)                 
#>  rlang        0.1.4   2017-11-05 CRAN (R 3.4.2)                 
#>  rmarkdown    1.8     2017-11-17 CRAN (R 3.4.2)                 
#>  rprojroot    1.2     2017-01-16 CRAN (R 3.4.0)                 
#>  scales       0.5.0   2017-08-24 CRAN (R 3.4.1)                 
#>  stats      * 3.4.3   2017-11-30 local                          
#>  stringi      1.1.6   2017-11-17 CRAN (R 3.4.2)                 
#>  stringr      1.2.0   2017-02-18 CRAN (R 3.4.0)                 
#>  tibble       1.3.4   2017-08-22 CRAN (R 3.4.1)                 
#>  tools        3.4.3   2017-11-30 local                          
#>  utils      * 3.4.3   2017-11-30 local                          
#>  withr        2.1.0   2017-11-01 CRAN (R 3.4.2)                 
#>  yaml         2.1.14  2016-11-12 CRAN (R 3.4.0)

Answer 1

windowsFonts(Times=windowsFont("Times New Roman"))

library(ggplot2)
 ggplot(data = diamonds, aes(x = carat, y = price)) + 
  geom_point() + 
  labs(title = "Diamantes: Quilates X Preço") + 
  theme(plot.title = element_text(family = "Times"))

EDITED:

My (perhaps erroneous) understanding of the problem:

Each graphic device has its own source bank available. These sources can be limited (hence the usefulness of extra source packages (p.e. extrafont), plus different names depending on the device:

The Function windowsFonts serves to "translate" from the graphic device (p.e. R) to the Windows system.