Didn't three of us give you a function (in various flavors) that would do the mean for variable inputs, reading them from a list? (Though David's was admittedly much cooler than mine!)
Anyways, look into parse(text=do) with eval() if you want to go the string route. Michael On Wed, Oct 5, 2011 at 4:14 PM, Martin Batholdy <batho...@googlemail.com> wrote: > Dear R-group, > > > is there a way to perform calculations that are defined in a string format? > > > for example I have different variables: > > x1 <- 3 > x2 <- 1 > x4 <- 1 > > and a string-variable: > > do <- 'x1 + x2 + x3' > > > Is there any way to perform what the variable 'do'-describes > (just like the formula-element but more elemental)? > > > > Perhaps my idea to solve my problem is a little bit strange. > > > My general problem is, that I have to do arithmetics for which there seems to > be no function available that I can apply in order to be more flexible. > > > To be precise, I have to add up three dimensional arrays. > > I can do that like this (as someone suggested on this help-list – thanks for > that!): > > (array[,,1] + array[,,2] + array[,,3]) / 3 > > > However in my case it can happen that at some point, I don't have to add 3 > but 8 'array-slices' > (or 10 or x). > > And I don't want to manually expand the above statement to: > > (array[,,1] + array[,,2] + array[,,3] + array[,,4] + array[,,5] + array[,,6] > + array[,,7] + array[,,8]) / 8 > > (ok, now I have done it ;) > > > > So, my thinking was that I can easily expand and change a string (with the > paste-function / repeat-function etc.). > But how can I expand a mathematical statement? > > > thanks for any suggestions! > ______________________________________________ > 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.
