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(mat, deriv, names(vals)) This bit seems to still work, but I'd welcome a solution that doesn't change the structure of the expression vector to a list, just in case. Thanks for this solution. > 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 > <jennifer.yo...@math.mcmaster.ca> wrote: >> Hallo >> >> I'm having trouble figuring out how to evaluate an expression when one >> of >> the variables in the expression is defined separately as a sub >> expression. >> Here's a simplified example >> >> mat <- expression(0, f1*s1*g1) # vector of formulae >> g1 <- expression(1/Tm) # expansion of the definition of g1 >> vals <- data.frame(f1=1, s1=.5, Tm=2) # one set of possible values for >> variables >> >> before adding this sub expression I was using the following to evaluate >> "mat" >> >> sapply(mat, eval, vals) >> >> Obviously I could manually substitute in 1/Tm for each g1 in the >> definition of "mat", but the actual expression vector is much longer, >> and >> the sub expression more complicated. Also, the subexpression is often >> adjusted for different scenarios. Is there a simple way of changing >> this >> or redefining "mat" so that I can define "g1" like a macro to be used in >> the expression vector. >> >> Thanks! >> Jennifer >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
