[R] Loop stopping after 1 iteration

[Martyn Byng]

Hi,

The answer to (2) is that num_obs is a scalar, so length(num_obs) is 1.

You probably wanted to do

for (i in 1:num_obs)

instead.

Best wishes

Martyn

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of armstrwa
Sent: 18 May 2011 16:18
To: r-help at r-project.org
Subject: [R] Loop stopping after 1 iteration

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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