Multiple left hand side variables in a formula
Gabor Grothendieck wrote
On Fri, Mar 1, 2013 at 7:16 PM, Frank Harrell <
f.harrell@
> wrote:
The lattice package uses special logic to allow for multiple left-hand-side variables in a formula, e.g. y1 + y2 ~ x. Is there an elegant way to do this outside of lattice? I'm trying to implement a data summarization function that logically takes multiple dependent variables. The usual invocation of model.frame( ) causes R to try to do arithmetic addition to create a single dependent variable.
Try: lm( cbind(Sepal.Length, Sepal.Width) ~., iris)
On Fri, Mar 1, 2013 at 8:02 PM, Frank Harrell <f.harrell at vanderbilt.edu> wrote:
Thanks for your reply Gabor. That doesn't handle a mixture of factor and numeric variables on the left hand side. Frank
It can handle 2 level factors lm(cbind(Sepal.Length, setosa = Species == "setosa") ~ ., iris) and more with some manual effort: lm(cbind(virginica = Species == "virginica", setosa = Species == "setosa") ~ ., iris) Typically you don't see more than that as a dependent variable. Do you actually need more? -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com