[R] possible inconsistency in nlme logLik or me

Hello, I am comparing 2 nonlinear models one with a correlation structure. I used the gnls command in the nlme package to fit model 1 and then the update(mod1,corr=corExp(form=~lat+lon,nugget=T) to fit the same model but with a correlation structure. I am comparing models using AIC, but I am ge

[R] refering to variable names in lm where the variable name is in another variable

I am trying to refer to a variable name in a lm regression where the variable name is in another variable, but it does seem to work. Here is an example: y<-rnorm(10) dat<-data.frame(x1=rnorm(10),x2=rnorm(10),x3=rnorm(10)) nam<-c('x1','x2','x3') library(gtools) com<-combinations(3,2,1:3) mod<-lm(

[R] distributing the values of data frame to a vector based on......

I am trying to distribute the entries of a data frame (dat) to a vector (water) based on the values of two other vectors (region and year). region is also the columns and year the rows of the data frame (dat). I can write a bunch of ifelse statements or I created the for statement below - but