Thomas, Here's a little bit of code to get you started. You can use the dist() function to calculate the absolute differences between all pairs of rows, then divide by 2 (as you requested), then convert the distance matrix to a vector. Do this for both groups of columns, and use cbind() to combine the results.
cbind(as.vector(dist(b[, 1:5], method="manhattan")/2), as.vector(dist(b[, 6:9], method="manhattan")/2)) Jean On Mon, Aug 5, 2013 at 1:39 AM, Kulupp <kul...@online.de> wrote: > # Dear R-experts, > > # (Once again) I want to avoid the usage of for-loops but unfortunately I > don't know how. > # I know functions like e.g. 'apply' but don't know how to use them for > the solution of the following problem: > # I have a data frame 'a' giving the number of columns in data frame 'b' > that belong to one group > a <- data.frame(group1=5, group2=4) > > b <- data.frame(col1=c(0,0,0), col2=c(0,1,0.5), col3=c(0,0,0), > col4=c(1/3,0,0.5), col5=c(2/3,0,0), > col6=c(0,0,0), col7=c(1,1/3,0), col8=c(0,2/3,0), > col9=c(0,0,0)) > > # ... thus columns 1-5 in 'b' belong to group 1 and columns 6-9 in 'b' > belong to group 2 > > # then I created a data frame giving all possible row combinations of 'b' > r <- as.data.frame(t(combn(nrow(b), 2))) > > # .. so e.g. the second row of 'r' tells me that I have to perform an > equation with the values of the > # first and third row of table 'b'. The equation has to be calculated for > each group seperately. > # e.g. within group 2 (columns 6-9 in 'b') I have to calculate e.g. for > rows 1 and 3 in 'b' > # (abs(b[row1,col6] - b[row3, col6]) + abs(b[row1, col7] - b[row3, > col7]) + .... + abs(b[row1, col9] - b[row3, col9]))/2 > > # the resulting data frame shall look as follows: > result <- cbind(r, data.frame(group1=c(1,2/3,0.5)**, > group2=c(2/3,0.5,0.5))) > > # The original tables are much larger and I don't know how to solve this > problem w/o a lot of very slow for-loops. > # Is there any possible solution w/o using 'for'-loops? > > # I'd be happy for any suggestions > # Thank you very much in anticipation > # Best regards > # Thomas > > ______________________________**________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.
