[R] Finding a vector position using names rather than values

Jonsson, Pall Pall.Jonsson at astrazeneca.com
Fri Sep 12 10:22:25 CEST 2008

Dear R gurus,

I have been struggling with this for a while and thought you might be able to give me some guidance.

I have a data frame, on which I apply a row function.  The result looks to me like a vector that retains the old row names.  I then sort the vector and subsequently need to be able to identify the rank of certain values by searching for their row names.  See this mock example:

> dframe <- data.frame("Col1"=c(10,20,30), "Col2"=c(2,4,6), "Col3"=c(5,10,7), row.names=c("R1","R2","R3"))
> row_median<-apply(dframe,1,median)
> row_median.sorted <- sort(row_median, decreasing=TRUE)

> row_median.sorted
R2 R3 R1 
10  7  5 

I now want to know the rank of, say R3 in this vector.  I know I can use match() to find this using the vector values, however I need to use the header names (eg. "R3") rather than the value (7).

Many thanks for your help,

More information about the R-help mailing list