[R] Question on lda and predict

[Erik Iverson]

Peter Flom wrote:
> Hello
> 
> Using R 2.7.0 on Windows.
> 
> I am running a linear discriminant analysis as follows
> 
> <<<<
> discrim1 <- lda(normvar~ mafmahal+  mrfmahal+ mffmahal+ bafmahal+ brfmahal+ 
>       cofmahal+ bmfmahal+ cfmahal+ fractmahal+ antmahal+ absmifmahal+ absifmahal, subset = train)
> prediction <- predict(discrim1, traintest1[-train,])$class
> 
> When I do this, I get a warning message:
> 
> <<<
> Warning message:
> 'newdata' had 795 rows but variable(s) found have 796 rows 
> 
> However, when I look at 'newdata' (i.e. traintest1) with dim, I find it has 796 rows:
> 
> <<<
>> dim(traintest1)
> [1] 796 612
> 

What happens when you do

dim(traintest1[-train,])

?

> So, I do not understand the warning.
> 
> Thanks for any explanation or assistance
> 
> Peter L. Flom, PhD
> Brainscope, Inc.
> 212 263 7863 (MTW)
> 212 845 4485 (Th)
> 917 488 7176 (F)
> 
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.