Hello Everyone! Here's what I'm trying to do. I'm working on generating occurrences of precipitation based upon precipitation occurrence for a station during the previous day and two stations that have already been generated by joint probablities and 1st order Markov chains or by the same generation process. This has to be done for each remaining stations for each month.
> genmat # 7 stations in this example, line_before is the climatology of the last day of the previous month. Stations 4 and 6 have been generated already in this example [,1] [,2] [,3] [,4] [,5] [,6] [,7] line_before 1 1 1 0 1 1 1 NA NA NA 1 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 1 NA 0 NA NA NA NA 1 NA 1 NA NA NA NA 1 NA 1 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 1 NA 1 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 1 NA 1 NA NA NA NA 0 NA 0 NA NA NA NA 1 NA 1 NA NA NA NA 1 NA 1 NA NA NA NA 1 NA 1 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 1 NA NA NA NA 0 NA 0 NA NA NA NA 0 NA 0 NA NA NA NA 1 NA 1 NA NA NA NA 1 NA 1 NA NA NA NA 1 NA 1 NA NA NA NA 0 NA 0 NA > num # station to generate [1] 2 > use1 # 1st station to use in generation [1] 6 > use2 # 2nd station to use in generation [1] 4 > genmat = event.gen2(genmat,use1,use2,num,ortho_obs_used) # Generation function shown below > genmat # genmat - after it has gone through station 2 [,1] [,2] [,3] [,4] [,5] [,6] [,7] line_before 1 1 1 0 1 1 1 NA 0 NA 1 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 1 NA 0 NA NA 1 NA 1 NA 1 NA NA 1 NA 1 NA 1 NA NA 1 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 1 NA 1 NA 1 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 1 NA 1 NA 1 NA NA 0 NA 0 NA 0 NA NA 1 NA 1 NA 1 NA NA 0 NA 1 NA 1 NA NA 1 NA 1 NA 1 NA NA 0 NA 0 NA 0 NA NA 1 NA 0 NA 1 NA NA 0 NA 0 NA 0 NA NA 0 NA 0 NA 0 NA NA 1 NA 1 NA 1 NA NA 1 NA 1 NA 1 NA NA 1 NA 1 NA 1 NA NA 0 NA 0 NA 0 NA Where event.gen2 is this function: event.gen2 = function(genmat,use1,use2,num,ortho_obs_used){ for(r in 2:nrow(genmat)){ ran = runif(1,0,1) if(genmat[r,use1]==0 & genmat[r,use2]==0){ genmat[r,num]<-ifelse(genmat[r-1,num]==0,ifelse(ran<ortho_obs_used$Pr[1],1,0),ifelse(ran<ortho_obs_used$Pr[4],1,0)) } if(genmat[r,use1]==0 & genmat[r,use2]==1){ genmat[r,num]<-ifelse(genmat[r-1,num]==0,ifelse(ran<ortho_obs_used$Pr[2],1,0),ifelse(ran<ortho_obs_used$Pr[5],1,0)) } if(genmat[r,use1]==1 & genmat[r,use2]==0){ genmat[r,num]<-ifelse(genmat[r-1,num]==0,ifelse(ran<ortho_obs_used$Pr[3],1,0),ifelse(ran<ortho_obs_used$Pr[7],1,0)) } if(genmat[r,use1]==1 & genmat[r,use2]==1){ genmat[r,num]<-ifelse(genmat[r-1,num]==0,ifelse(ran<ortho_obs_used$Pr[6],1,0),ifelse(ran<ortho_obs_used$Pr[8],1,0)) } gc() } genmat } #### ortho_obs_used is a data frame that contains the probablity of precipitation occurring on a given day for a specific set of condtions. For instance ortho_obs_used$Pr[1] is the probablity of rain at station s for day d, given that there was no rain at station s for day d-1 and no rain at either of the other two stations for day d. The event.gen2 function handles the generation, and it runs quickly for the 5 remaining stations and one month, but I have to run this for 317 stations over 48 months or more, and it becomes a really bad bottleneck. So what I'd like to know is if there is anyway that I can re-write this function to work without a loop. I couldn't find anything from previous posts about getting out of loops where the previous iteration is required to determine the next calculation. Sorry for the length of the post, but I thought it best to try to explain what I was doing first, before diving into my question Thanks in advance! Adrienne Wootten Graduate Research Assistant/Environmental Meteorologist M.S. Atmospheric Science NC State University State Climate Office of North Carolina Raleigh, NC 27695 [[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.