Re: collapse to unique row.names using mean()

[John Fox <jfox@mcmaster.ca>]

Dear Phillip,

Your example suggests that the rows with duplicate names are contiguous. If 
this is the case, then the following should do what you want without using 
a lot of memory (where df is the data frame):
rows <- c("",row.names(df))
keep <- 1:nrow(df)
for (i in 1:nrow(df)) if (rows[i+1] == rows[i]) keep[i] <- 0
df <- df[keep,]

I hope that this helps,
 John

At 12:33 AM 1/19/2003 -0700, Phillip Staford wrote:
> Dear S group;
>
> I'm looking for a very low-memory (slow is OK, but memory is critical 
> here) method to collapse a data.frame that has a mixture of unique and 
> replicated row.names.  What's the best way to do this without burning 
> unnecessary memory?
> A  3
> A  2
> A  1
> B  3
> C  2
> C  4
> into
> A  2
> B  3
> C  3
>
>
> Thanks for any suggestions, the obvious ways are quick but not memory 
> efficient I think.
-----------------------------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox@mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
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