Hi, I have a data.frame which contains timeseries from several different locations, which I want to compare against each other for example calculating RMSE, or normalized mean bias of each location against the others. An example of this is the cor function where I can put in a data.frame and get the correlation of each location compared to the others in the data.frame eg. cor(data.frame(a=runif(10),b=runif(10),c=runif(10),d=runif(10))) Is there any generic way of getting this for other functions, such as the aggregate or lapply functions? I have read their documentation, but was unclear as to how I might use them to get a matrix like the cor function. I could do this using a pair of loops, but was hoping there might be a more general way of creating such a matrix of any comparison function. Thank you for your help, -- Neil Davis Ph.d.-student DTU Wind Energy Technical University of Denmark Department of Wind Energy Ris? Campus Frederiksborgvej 399, P.O. Box 49 Building 125 4000 Roskilde Direct +45 46775067 neda at dtu.dk <mailto:neda at dtu.dk> www.dtu.dk <http://www.dtu.dk>
On Apr 26, 2012, at 9:29 AM, Neil Davis wrote:> Hi, > > I have a data.frame which contains timeseries from several different > locations, which I want to compare against each other for example > calculating RMSE, or normalized mean bias of each location against > the others. An example of this is the cor function where I can put > in a data.frame and get the correlation of each location compared to > the others in the data.frame eg. > cor(data.frame(a=runif(10),b=runif(10),c=runif(10),d=runif(10))) > > Is there any generic way of getting this for other functions, such > as the aggregate or lapply functions? I have read their > documentation, but was unclear as to how I might use them to get a > matrix like the cor function. I could do this using a pair of loops, > but was hoping there might be a more general way of creating such a > matrix of any comparison function.Perhaps you are looking for: ?tapply -- David Winsemius, MD West Hartford, CT