[R-sig-eco] a question for save CSV files in the 'for loop' codes

[Will Morris]

The problem is you're using the same filename for each call to write.
The for loop is unaware of the i in "F:/pixel_no[i].csv" as it is
hidden by the quote marks. You need to use the paste function to
create a new file name for each iteration.

Will Morris
Masters of Philosophy candidate
Vesk Plant Ecology Lab
The School of Botany
The University of Melbourne
Australia
Phone: +61 3 8344 0120
http://www.botany.unimelb.edu.au/vesk/

On 25/12/2009, at 19:38, Zongshan Li <zongshan_li at yahoo.com> wrote:

> Dear the friends of R-Ecology:
>      I am a beginner for R language, I have a question, maybe very
> simple, to save CSV file in the ‘for loop’ function.
>
> The code is just following:
>
> rownames(pre1901_1920)<-pre1901_1920[,1]
> pixel_no<-rownames(pre1901_1920)
>
> for(i in 1:100)
> {
> data01<-matrix(pre1901_1920[i,2:241],ncol=12,byrow=T)
> data02<-matrix(pre1921_1940[i,2:241],ncol=12,byrow=T)
> data03<-matrix(pre1941_1960[i,2:241],ncol=12,byrow=T)
> data04<-matrix(pre1961_1980[i,2:241],ncol=12,byrow=T)
> data05<-matrix(pre1981_2000[i,2:241],ncol=12,byrow=T)
> data<-rbind(data01,data02,data03,data04,data05)
> colnames(data)<-c
> ('j
> an','feb','mar','apr','may','jun','jul','aug','sep','oct','nov','dec')
> rownames(data)<-1901:2000
> write.csv(data,file="F:/pixel_no[i].csv")
> }
> The variables of ‘pre1901_1920’, ‘pre1921_1940’,
> ‘pre1941_1960’, ‘pre1961_1980’ and ‘pre1981_2000’ are
> downloaded precipitation data from CRU TS 2.1 Global Climate dataset
>  for a special 5*5 degree region lasting from 1901-2000.
>
> The first column of each variable is the special values for 100
> pixels of this CRU dataset (such as 51447, 51582, 51584, 51573
> etc.), while the rows (2:241) of each variable are the monthly
> precipitation data for 20 years.
>
> I want to reshape the original dataset to the dataset for each
> pixel, which is a 100-raw and 12-colunm matrix to represent the
> monthly precipitation data lasting from 1901 to 2000 in each pixel;
> and each such matrix (100*12) is subsequently saved by a special CSV
> file(the file name is the value of that pixel).
>
> All the codes run well, except for the last row (I am wondering why
> only save a single CSV file?). My question is that how to save the
> 100 matrixes (100*12) generated in the ‘for loop’ function to
> different CSV files with the pixel values as the file title names.
>
> Any help is strongly appreciated,
> thank you in advance,
> Merry Christmas to you!
>
> ----------------------
> Zongshan, Li
> 2009-12-25
> Research Center for Eco-Environmental Sciences,Chinese Academy of
> Sciences
> Shuangqing Road, Haidian street, Beijing, 100085
> Tel: 86-10-13699145748
> QQ: 1141958023
> email: ZongShan_Li at yahoo.com
> website: http://www.rcees.ac.cn/
>
>
>
>    [[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-ecology mailing list
> R-sig-ecology at r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology