[R] Eliminate cases in a subset of a dataframe
Hollix
Holger.steinmetz at web.de
Mon Sep 14 16:57:40 CEST 2009
Hi folks,
I created a subset of a dataframe (i.e., selected only men):
subdata <- subset(data,data$gender==1)
After a residual diagnostic of a regression analysis, I detected three
outliers:
linmod <- lm(y ~ x, data=subdata)
plot(linmod)
Say, the cases 11,22, and 33 were outliers.
Here comes the problem: When I want to exclude these three cases in a
further regression analysis,
- for instance with linmod2 <- lm(y[-c(11,22,33)] ~ x[-c(11,22,33)],
data=subdata) - it does not work.
I guess this has something to do with this strange "row.names"-vector which
has been added to the dataframe when creating the subset. I find it very
strange why R gives the case numbers in the diagnostics but then doesn't
allow me to use these numbers for further exclusion.
Can anybody tell me:
1. what this row.names vector is
2. How I can refer to cases after creating a subset (e.g., in order to
exclude them).
Many thanks in advance,
Best,
Holger
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