Hi all, I would like to apply a function to each column of an 2-dimensional array, and store the result in a new 1-dimensional vector. I am not sure how to go about doing that syntatically. For instance, can I use lapply? And, if so, how do I specify which dimension should be used? Also, how do I pre-specify the type of object that will go into the 1-dimensional vector. I'm not sure if it is important, the function I wish to apply to the columns is density(). Additionally, I wish to be able to take these density objects (stored in that 1-dim vector) and place them onto a multiple-figure environment. I'm new with R, so I tend to think in loops. I'd appreciate any guidance or tips on better ways to handle this problem. Thanks! Paul -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Apply function to column of array
2 messages · Paul Boutros, Roger D. Peng
It seems that for this you may in fact want to use a loop. If you have a
matrix with p columns (say it's called 'm'), then you might consider:
results <- vector("list", length = p)
for(i in 1:p) results[[i]] <- density(m[,i])
If you want to use lapply() then something like the following should work:
results <- lapply(1:p, function(i) density(m[,i]))
Then 'results' is a vector of lists which contain the results to the
individual calls to density(). You can then cycle over this vector to
make your plots or whatever.
-roger
_______________________________
UCLA Department of Statistics
rpeng at stat.ucla.edu
http://www.stat.ucla.edu/~rpeng
On Tue, 29 Oct 2002, Paul Boutros wrote:
Hi all, I would like to apply a function to each column of an 2-dimensional array, and store the result in a new 1-dimensional vector. I am not sure how to go about doing that syntatically. For instance, can I use lapply? And, if so, how do I specify which dimension should be used? Also, how do I pre-specify the type of object that will go into the 1-dimensional vector. I'm not sure if it is important, the function I wish to apply to the columns is density(). Additionally, I wish to be able to take these density objects (stored in that 1-dim vector) and place them onto a multiple-figure environment. I'm new with R, so I tend to think in loops. I'd appreciate any guidance or tips on better ways to handle this problem. Thanks! Paul -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._