knit_expand(text = "The value of pi is {{pi}}.")
knit_expand(text = "The value of a is {{a}}, so a + 1 is {{a+1}}.", a = rnorm(1))
knit_expand(text = "The area of a circle with radius {{r}} is {{pi*r^2}}", r = 5)
## any number of variables
knit_expand(text = "a is {{a}} and b is {{b}}, with my own pi being {{pi}} instead of {{base::pi}}",
a = 1, b = 2, pi = 3)
## custom delimiter <\% \%>
knit_expand(text = "I do not like curly braces, so use % with <> instead: a is <% a %>.",
a = 8, delim = c("<%", "%>"))
## the pyexpander delimiter
knit_expand(text = "hello $(LETTERS[24]) and $(pi)!", delim = c("$(", ")"))
## arbitrary R code
knit_expand(text = "you cannot see the value of x {{x=rnorm(1)}}but it is indeed created: x = {{x}}")
knit_expand(text = c("x | x^2", "{{x=1:5;paste(sprintf("%2d | %3d", x, x^2), collapse = "\n")}}"))
## the m4 example: http://en.wikipedia.org/wiki/M4_(computer_language)
knit_expand(text = c("{{i=0;h2=function(x){i<<-i+1;sprintf("<h2>%d. %s</h2>", i, x)} }}<html>",
"{{h2("First Section")}}", "{{h2("Second Section")}}", "{{h2("Conclusion")}}",
"</html>"))
## build regression models based on a template; loop through all vars in mtcars
src = lapply(names(mtcars)[-1], function(i) {
knit_expand(text = c("# Regression on {{i}}", "```{r lm-{{i}}}", "lm(mpg~{{i}}, data=mtcars)",
"```"))
})
# knit the source
cat(knit(text = unlist(src)))Run the code above in your browser using DataLab