On 18 Nov 2003 at 21:53, Martin Wegmann wrote: You can go by text representation in a loop, using some of the following stuff:
> form <- "y ~ x " > as.formula(form) y ~ x > nchar(form) [1] 8 > substr(form, 7,8) [1] " " > substr(form, 7,8) <- "+z" > form [1] "y ~ x +z" > as.formula(form) y ~ x + z > Then you can loop over (part of) names(your.df) Kjetil Halvorsen > On Tuesday 18 November 2003 19:32, Prof Brian Ripley wrote: > > On Tue, 18 Nov 2003, Martin Wegmann wrote: > > > I have count data of animals (here y, y1, y2...) and env. > > > variables (x, x1, x2 ,....). > > > > > > I used a glm > > > > > > glm(y~x1+x2+x3....) > > > > > > glm(y1~x1+x2+x3....) > > > > > > and now I would like to add the count data of other species to > > > investigate if they might have a bigger impact than the env. > > > variables: > > > > > > #x? are the selected var from the first glm run > > > > > > glm(y~x?+x?+y1) > > > > > > glm(y~x?+x?+x?+y2) > > > > > > .... > > > > > > I wonder if there is a more elegant method to do this than adding > > > (and removing) each y by hand. > > > > Do you mean each x? In either case, see ?update. > > update looks good but with update and with adding the y I have to do > it manually. > > I thought something like doing > > glm(y~x+x1+x2+....+y�) > > where y� is: grep y1 out of df.y run glm and name it > grep y2 out of df.y run glm ..... > > until all y's of df.y has been onced included in the model. > every time only one y� has to be included > > the included x's have to be kept. I only want to look if one species > variables has more explanation power than the env. variables. > > perhaps this helps to understand what I am looking for: > I think bash scripts are not possible in R but it would look like such > a bash script for GRASS: > > for variable in y1 y2 y3 ....; do > > glm(y~x+x1+x2....+$variable)->glm.$variable > ; done > > #where $variable refers to the name of read in y's. > > > Martin > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
