How to evaluate a variable and print as a string/character in R?

Question

I've tried finding this on SO without any luck:

How do I convert a closure object into a string in R?

I have a list of functions, like this:

functions = c(function(x) 2*x, function(x) sin(x*pi), function(x))

And, I iterate over them like for (func in functions){..., and I'd like to be able print the function expression as part of my plotting.

I've tried:

toString(eval(func))
as.character(eval(func))

What gives?

Related links:

The closest I can get is this: `as.character(parse(text=as.list(func)))` — buzzinolops, Apr 11 '16 at 03:50
doesnt as.character(parse(text=func)) achieve what you want? — chinsoon12, Apr 11 '16 at 03:51
No, it throws an error: `Error in as.character(x) : cannot coerce type 'closure' to vector of type 'character'` — buzzinolops, Apr 11 '16 at 03:52
wah more complicated than i think haha... check this out http://stackoverflow.com/questions/31421462/convert-any-r-variables-value-to-string someone also solved this using capture.output — chinsoon12, Apr 11 '16 at 04:06
temp <- lapply(functions, function(func) capture.output(func)); lapply(temp, class) — chinsoon12, Apr 11 '16 at 04:07
What are you trying to do with them? You can chuck them in a list, or wrap the expression in `quote` (or `expression`) for easy `eval` later, but the best approach depends on what you're trying to do. — alistaire, Apr 11 '16 at 04:17

score 0 · Answer 1 · answered Apr 11 '16 at 04:17

0

There seems to be no easy way to accomplish this. Here is the best way I found:

as.character(parse(text=as.list(func)))

For a more general solution, you can capture the output, as @chinsoon said.

answered Apr 11 '16 at 04:17

buzzinolops

1 Answers1