[Rd] Getting ordered factor levels from C

Mark Lilback mlilback at stat.wvu.edu
Wed Oct 24 20:14:07 CEST 2012

I'm working on an R package in C and can't seem to get the same level information about a factor that the R console displays.

If I define a factor as:

lvls <- factor(c('red','blue','blue','green','red'), c('blue','green','red'), ordered=TRUE)

When I get the "levels" attribute in C, I get back the the first vector, not the second. If I run attr(lvls,"levels") in R, I get back the second vector. There are no attributes besides class and levels, so how do I get the list of levels in the correct order?


Mark Lilback
West Virginia University Department of Statistics
mlilback at stat.wvu.edu

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