I am trying to extract the shape and scale parameters of a wind speed distribution for different sites. I can do this in a clunky way, but I was hoping to find a way using data.table or plyr. However, when I try I am met with the following:
set.seed(144) weib.dist<-rweibull(10000,shape=3,scale=8) weib.test<-data.table(cbind(1:10,weib.dist)) names(weib.test)<-c('site','wind_speed') fitted<-weib.test[,fitdistr(wind_speed,'weibull'),by=site] Error in class(ans[[length(byval) + jj]]) = class(testj[[jj]]) : invalid to set the class to matrix unless the dimension attribute is of length 2 (was 0) In addition: Warning messages: 1: In dweibull(x, shape, scale, log) : NaNs produced ... 10: In dweibull(x, shape, scale, log) : NaNs produced (the warning messages are normal from what I can tell) or using plyr: set.seed(144) weib.dist<-rweibull(10000,shape=3,scale=8) weib.test.too<-data.frame(cbind(1:10,weib.dist)) names(weib.test.too)<-c('site','wind_speed') fitted<-ddply(weib.test.too,.(site),fitdistr,'weibull') Error in .fun(piece, ...) : 'x' must be a non-empty numeric vector those sound like similar errors to me, but I can't figure out how to make them go away! to prove I'm not crazy: fitdistr(weib.dist,'weibull')$estimate shape scale 2.996815 8.009757 Warning messages: 1: In dweibull(x, shape, scale, log) : NaNs produced 2: In dweibull(x, shape, scale, log) : NaNs produced 3: In dweibull(x, shape, scale, log) : NaNs produced 4: In dweibull(x, shape, scale, log) : NaNs produced Thanks Justin ______________________________________________ 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.