Marine -
Assuming your data frame is named "df", I think
apply(df,1,function(x)mean(x[x[7]:x[8]]))
will give you what you're looking for.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Thu, 10 Feb 2011, Marine Andersson wrote:
Hello!
I have a dataset like this:
X1 X2 X3 X4 X5 X6 X7 X8
1 2 2 1 2 3 2 6
2 3 2 5 7 9 1 3
1 9 12 6 1 1 3 6
The columns X1-X6 contains ordinary numeric values.
X7 contains the number of the first column that the rowMeans should be
calculated from and
X8 contains the last column that should be included in the rowMeans.
when I try
test <- (df[,df$X7:df$X8])
the rowMeans are calculated based on the values in the X7 and X8 in the first
row only.
Thanks in advance!
/Marine
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