translating a character string

2 messages · Erin Hodgess, Rolf Turner

Tue, Oct 18, 2011 5:57 PM #

Dear R People:

Suppose I have the following character string:

[1] "(1/30)*(20-x)"

My goal is to end up with
y <- (1/30)*(20-x)

How would I do this, please?

I've been experimenting with eval, but no good so far.

As usual, I have the feeling that this is something really simple, but
I can't quite get it.

Thank you in advance for any help.


Sincerely,
Erin

Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

Rolf Turner

Tue, Oct 18, 2011 6:27 PM #

On 19/10/11 13:57, Erin Hodgess wrote:

Irrespective of fortune("parse"), parse() is what you need:

f1 <- "(1/30)*(20-x)"
x <- 42
y <- eval(parse(text=f1))
y
[1] -0.7333333

     cheers,

         Rolf