Hi, set.seed(45) testframe <- data.frame(a=rnorm(100), b = rnorm(100)) indices <- rep(c(1,2), each = 50) library(plyr)
ddply(testframe,.(indices),summarize, Cor1=cor(a,b)) # indices Cor1 #1 1 0.002770524 #2 2 -0.101738888 A.K. ----- Original Message ----- From: Jannis <bt_jan...@yahoo.de> To: Greg Snow <538...@gmail.com> Cc: r-help <r-help@r-project.org> Sent: Friday, June 28, 2013 4:31 AM Subject: Re: [R] multivariate version of aggregate Yes, I had a look at that function. From the documentation, however, it did not get clear to me how to split the dataframe into subsets of rows based on an index argument. Like: testframe <- data.frame(a=rnorm(100), b = rnorm(100)) indices <- rep(c(1,2), each = 50) results <- ddply(.data = testframe, INDICES= indices, .fun = function(x) corr(x[,1], x[,2])) Where the last command would yield the correlations between column 1 and 2 of the first 50 and of the last 50 values. Any ideas? Jannis On 27.06.2013 21:43, Greg Snow wrote: > Look at the plyr package, probably the ddply function in that package. You > can write your own function to do whatever you want on the pieces of the > split apart object. Correlation between a specified pair of columns would > be simple. > > > On Thu, Jun 27, 2013 at 11:26 AM, Jannis <bt_jan...@yahoo.de> wrote: > >> Dear List members, >> >> >> i am seeking a multivariate version of aggregate. I want to compute, fro >> example the correlation between subsets of two vectors. In aggregate, i can >> only supply one vector with indices for subsets. Is there ready function >> for this or do i need to program my own? >> >> >> Cheers >> Jannis >> >> ______________________________**________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> >> PLEASE do read the posting guide http://www.R-project.org/** >> posting-guide.html <http://www.R-project.org/posting-guide.html> >> and provide commented, minimal, self-contained, reproducible code. >> > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
