Put a frame around text fields in R base plots

Question

I have a simple scatter plot, where I want to add some text fields. Additionally, I want to put a frame around them.

Here is a toy example:

set.seed(1)
x <- rnorm(10)
y <- rnorm(10)

plot(x,y)

text(0,0,'FRAME ME PLEASE')

Answer 1

It's possible to do this dynamically if you calculate the width and height of the string in plotting units:

set.seed(1); x <- rnorm(10); y <- rnorm(10); plot(x,y)

txt <- 'FRAME ME PLEASE'
xt <- 0
yt <- 0

text(xt, yt, txt)

sw   <- strwidth(txt)
sh   <- strheight(txt)
frsz <- 0.05

rect(
  xt - sw/2 - frsz,
  yt - sh/2 - frsz,
  xt + sw/2 + frsz,
  yt + sh/2 + frsz
)

It is worth noting that this can also deal with cex and font changes in the width and height calculation stages if specified.

Answer 2

Here's another option making legend do the work.

legend(0, 0, "FRAME ME PLEASE",
    xjust = 0.5,      # 0.5 means center adjusted
    yjust = 0.5,      # 0.5 means center adjusted
    x.intersp = -0.5, # adjust character interspacing as you like to effect box width
    y.intersp = 0.1,  # adjust character interspacing to effect box height
    adj = c(0, 0.5))  # adjust string position (default values used here)
    # cex = 1.5,      # change cex if you like (not used here)
    # text.font = 2)  # bold the text if you like (not used here)