On 2010.05.25 11:52:07, Anyi Zhu wrote: > Hi, > > I am a novice with R, so pardon me if the question is a piece of cake > to some of you. > > Say if I have a stream of data consisting of 3 columns, 1st column is > birth date, 2nd is death date and third is weight for each individual. > > My ultimate goal is to be able to compute the correlation of weight > between any combination of two death dates, grouped by birth dates. > > In order to do this, my plan is to be able to use a loop of some sorts > to split the data into n vectors, each vector consists of all birth > dates and weight for people who are dead on the same death date. Then > figure out the standard deviation and covariance of each of the > combination of the vectors, figure out the correlation and finally > bind them into a matrix (or at least a 3 column table: death date1, > death date 2, correlation). > > The only problem is I know how to implement this in SQL/Excel but not in R. > > Could someone please offer me some guidance on this? Thanks a lot!
Hello Anyi, I suggest you take a look at the plyr package. It allows you to easily subset a data.frame and apply any function to that data.frame. HTH, ~Jason -- Jason W. Morgan Graduate Student Department of Political Science *The Ohio State University* 154 North Oval Mall Columbus, Ohio 43210 ______________________________________________ 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.
