[R] Loop stopping after 1 iteration

[Hugo Mildenberger]

William,

num_obs obviously isn't a vector, therefore length(num_obs) will
evaluate to one. Hence your for loop control part will expand to 

        for (i in 1:1) 

while it should probably read:

        for (i in 1:num_obs)

Best

Hugo

On Wednesday 18 May 2011 17:18:15 armstrwa wrote:
> Hi all,
> 
> This is a very basic question, but I just can't figure out why R is handling
> a loop I'm writing the way it is.
> 
> Here is the script I have written:
> 
> grid_2_series<-function(gage_handle,data_type,filename)
> 
> series_name<-paste(gage_handle,data_type,sep="_")
> data_grid<-read.table(file=paste(filename,".txt",sep=""))
> 
> num_rows_data<-nrow(data_grid)-1
> num_cols_data<-ncol(data_grid)-4
> num_obs<-num_rows_data*num_cols_data
> 
> time_series<-matrix(nrow=0,ncol=2)
> 
> for(i in 1:length(num_obs)){
> 	rownum<-ceiling(i/31)+1
> 	colnum<-if(i%%31==0){
> 			35
> 		}else{
> 			(i%%31)+4
> 		}
> 	year<-data_grid[rownum,2]
> 	month<-data_grid[rownum,3]
> 	day<-colnum-4
> 	date_string<-paste(month,day,year,sep="/")
> 	date<-as.Date(date_string,format='%m/%d/%Y')
> 	value<-as.character(data_grid[rownum,colnum])
> 	time_series<-rbind(time_series,c(date,value))
> }
> 
> The script is working as I intended it to (goes through a matrix of data
> where column 2 is the year, column 3 is the month, and row 1 columns 5-35
> are the day of the month the observation was recorded [I have included a
> screenshot below to help visualize what I'm talking about] and converts the
> grid into a 2 column time series where column 1 is the date and column 2 is
> the value of the observation), but it is stopping after only 1 iteration.
> 
> nabble_img src="matrix_screenshot.jpg" border="0"/>
> 
> Two questions:
> 
> 1.) Does anyone know of an existing function to accomplish this task?
> 2.) Why is the loop stopping after 1 iteration?  I have it written to
> iterate up to the total number of observations (20,615 in one case).
> 
> Thank you for your help and sorry for this question which I'm sure has a
> very simple answer.
> 
> Thanks again,
> 
> Billy<
> 
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