[R] indexing a subset dataframe

Chuck Cleland ccleland at optonline.net
Mon Apr 16 10:21:01 CEST 2007

Mandy Barron wrote:
> Hello
> I am having problems indexing a subset dataframe, which was created
> as:
>> waspsNoGV<-subset(wasps,site!="GV")
> Fitting a linear model revealed some data points which had high
> leverage, so I attempted to redo the regression without these data
> points:
>> wasps.lm<-lm(r~Nt,data=waspsNoGV[-c(61,69,142),])
> which resulted in a "subscript out of bounds" error.
> I'm pretty sure the problem is that the data points identified in the
> regression as having high leverage were the row names carried over from
> the original dataframe which had 150 rows, but when I try to remove data
> point #142 from the subset dataframe this tries to reference by a
> numerical index but there are only 130 data points in the subset
> dataframe hence the "subscript out of bounds" message.  So I guess my
> question is how do I reference the data points to drop from the
> regression by name?

  Does this do it?

wasps.lm <- lm(r ~ Nt, data = subset(wasps, site != "GV" &
!(rownames(wasps) %in% c(61,69,142)))

> Thanks
> Mandy
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Chuck Cleland, Ph.D.
NDRI, Inc.
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