On Sat, Jan 30, 2010 at 10:39 AM, Jennifer Young
wrote:
> handling of variables in R to be very straightforward; sometimes I pine
> for Maple to do my algebra for me...
There are several interfaces to Computer Algebra Systems in R. Try
this (but read instructions on home page
http://ryacas.goo
ot what we want!
>> ## And sure enough ...
>>> eval(f)
>> Error in a * expression(1/t) : non-numeric argument to binary operator
>>
>> I think I understand why the z <- expression() approach does not work;
>> but I
>> do not understand why the z <- quote(
Inline below...
-Original Message-
From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com]
Sent: Friday, January 29, 2010 2:12 PM
To: Bert Gunter
Cc: Jennifer Young; r-help@r-project.org
Subject: Re: [R] evaluating expressions with sub expressions
If its good enough to have one level
dentical()
> tells me so). Could someone perhaps elaborate on this a bit more? And is
> there a yet simpler and more straightforward way to do the above than what I
> proposed?
>
> Cheers,
>
> Bert Gunter
> Genentech Nonclinical Statistics
>
>
> -Original Message--
-Original Message-
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Bert Gunter
> Sent: Friday, January 29, 2010 1:38 PM
> To: 'Gabor Grothendieck'; 'Jennifer Young'
> Cc: r-help@r-project.org
> Subject: Re: [R]
re straightforward way to do the above than what I
proposed?
Cheers,
Bert Gunter
Genentech Nonclinical Statistics
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Gabor Grothendieck
Sent: Friday, January 29, 2010 11:01 AM
To: Jenn
The following recursively walks the expression tree. The esub
function is from this page (you may wish to read that entire thread):
http://tolstoy.newcastle.edu.au/R/help/04/03/1245.html
esub <- function(expr, sublist) do.call("substitute", list(expr, sublist))
proc <- function(e, env = parent.f
Hmm
I *think* this will work, but may break in a further sub routine.
It certainly works in this example, but my expression vector is used in
many scenarios and it will take a while to check them all.
For instance, I take the derivative of each element with respect to each
variable using
sapply(
Hi,
Would this do as an alternative syntax?
g1 <- quote(1/Tm)
mat <- list(0, bquote(f1*s1*.(g1)))
vals <- data.frame(f1=1, s1=.5, Tm=2)
sapply(mat, eval, vals)
HTH,
baptiste
On 29 January 2010 17:51, Jennifer Young
wrote:
> Hallo
>
> I'm having trouble figuring out how to evaluate an expres
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