r - User defined functions as formula input -

built-in functions in r can used in formula objects, example

reg1 = lm(y ~ log(x), data = data1) 

how can write functions such can used in formula objects?

fnmyfun = function(x) {   return(x^2) } reg2  = lm(y ~ fnmyfun(x), data = data1) 

what you've got works. 1 problem different modelling functions handle formulas in different ways. think long return model.matrix can make sense of, you'll fine. mean

1. the function vectorised; ie given vector of length n, returns result of length n

2. it has return atomic vector or matrix (but not list, or of type raw)