Question

When using pairs() I like using the suggested functions panel.cor and panel.hist (which are suggested in the examples) to eliminate the duplicated upper or lower triangular space and provide extra information.

I would like to source those functions using something like

source(example(pairs, ask = F, echo = F))

and not get any output (including: Error in readLines(file, warn = FALSE) : 'con' is not a connection), and not have the example plots print. Is this possible?

As I side note, the reason I’d like the plots not to print is that I want to use this in an R Markdown file and not have to look at the example(pairs) plots in my document.

Answer 1

You could run a chunk that is not included, and does not keep the figures. The functions will be available as the code is run, but the output not included in the document.

```{r example_pairs, include = F, fig.keep = 'none'}
example(pairs)
```

```{r test}
exists('panel.cor')
```

The output looks like

exists("panel.cor")

## [1] TRUE

panel.cor exists in the global environment — you can use it.

EDIT alternative

You could also use the give.lines argument and save the source code yourself

.ex <- example(pairs, give.lines = T)
# find the code in question (look for assignment / scope delimiters)
which(grepl(.ex, pattern = "(panel.hist <-)|(panel.cor <-)|[{}]"))
##[1] 18 19 26 33 34 42

cat(.ex[c(18:26, 33:42)], sep = "\n")
panel.hist <- function(x, ...)
{
    usr <- par("usr"); on.exit(par(usr))
    par(usr = c(usr[1:2], 0, 1.5) )
    h <- hist(x, plot = FALSE)
    breaks <- h$breaks; nB <- length(breaks)
    y <- h$counts; y <- y/max(y)
    rect(breaks[-nB], 0, breaks[-1], y, col="cyan", ...)
}
panel.cor <- function(x, y, digits=2, prefix="", cex.cor, ...)
{
    usr <- par("usr"); on.exit(par(usr))
    par(usr = c(0, 1, 0, 1))
    r <- abs(cor(x, y))
    txt <- format(c(r, 0.123456789), digits=digits)[1]
    txt <- paste(prefix, txt, sep="")
    if(missing(cex.cor)) cex.cor <- 0.8/strwidth(txt)
    text(0.5, 0.5, txt, cex = cex.cor * r)
}