gstat.formula.R
# $Id: gstat.formula.q,v 1.8 2007-06-08 06:45:52 edzer Exp $
"gstat.formula" <-
function (formula, data)
{
m = model.frame(terms(formula), as(data, "data.frame"))
Y = model.extract(m, "response")
if (length(Y) == 0)
stop("no response variable present in formula")
Terms = attr(m, "terms")
X = model.matrix(Terms, m)
has.intercept = attr(Terms, "intercept")
if (gridded(data))
grid = gridparameters(data)
else
grid = numeric(0)
list(y = Y, locations = coordinates(data), X = X, call = call,
has.intercept = has.intercept, grid = as.double(unlist(grid)))
}