[R] Q: selecting a name when it is known as a string

[D. R. Evans]

I am 100% certain that there is an easy way to do this, but after
experimenting off and on for a couple of days, and searching everywhere I
could think of, I haven't been able to find the trick.

I have this piece of code:

...
  attach(d)

  if (ORDINATE == 'ds')
  { lo <- loess(percent ~ ncms * ds, d, control=loess.control(trace.hat =
'approximate'))
    grid <- data.frame(expand.grid(ds=MINVAL:MAXVAL, ncms=MINCMS:MAXCMS))
...

then there several almost-identical "if" statements for different values of
ORDINATE. For example, the next "if" statement starts with:

...
  if (ORDINATE == 'dsl')
  { lo <- loess(percent ~ ncms * dsl, d, control=loess.control(trace.hat =
'approximate'))
    grid <- data.frame(expand.grid(dsl=MINVAL:MAXVAL, ncms=MINCMS:MAXCMS))
...

This is obviously pretty silly code (although of course it does work).

I imagine that my question is obvious: given that I have a variable,
ORDINATE, whose value is a string, how do I re-write statements such as the
"lo <-" and "grid <-" statements above so that they use ORDINATE instead of
the hard-coded names "ds" and "dsl".

I am almost sure (almost) that it has something to do with "deparse()", but
I couldn't find the right incantation, and the ?deparse() help left my head
swimming.