On Mon, 10 Nov 2003, Edzer J. Pebesma wrote: > I was surprised by the following (R 1.8.0): > > R> lm.fit = lm(y~x, data.frame(x=1:10, y=1:10)) > R> predict(lm.fit, data.frame(x = rep(NA, 10))) > 1 2 3 4 5 > -1.060998e-314 -1.060998e-314 -1.060998e-314 -1.060998e-314 -1.060998e-314 > 6 7 8 9 10 > 0.000000e+00 1.406440e-269 6.715118e-265 4.940656e-323 1.782528e-265 > R> predict(lm.fit, data.frame(x = as.numeric(rep(NA, 10)))) > 1 2 3 4 5 6 7 8 9 10 > NA NA NA NA NA NA NA NA NA NA > > shouldn't the first predict() call return NA's, or else issue an error > message?
The prediction methods do not in general check that new variables you give are of the correct type: the type used in the fit is not recorded in the model object. In this case a logical column will `work' provided it has two values (even with NAs). We can probably trap this exact case, but there will remain a lot of scope for user error. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
