CODEWITHSUNDEEP
rnetcdf
sacvf
sacvf

Reputation: 2533

why first value is repeated when doing a loop in R?

I have several netcdf files that i want to extract to text file but I found that the first value (from the first file)of A,B,Cin the output file es55.txt is repeated for the whole text file so the loop does not take values from other files the code:

    library("ncdf")
 a<-list.files("C:\\Users\\CLdata", "*.nc", full.names = TRUE)
 dt <-   as.POSIXct(strptime(basename(a), "data_%Y%m%dT%H%M%S_%Y%m%dT%H%M%S", tz = "GMT"))
 for(i in 1:length(a)){
  f <- open.ncdf(a[i])
  A = get.var.ncdf(nc=f,varid="Sgf",verbose=TRUE)
  B <- get.var.ncdf(nc=f,varid="gh")
  C <- get.var.ncdf(nc=f,varid="jk")
  df=data.frame(date = dt, A, B ,C ) }
   write.table(df,file="es55.txt")

example:

    "date" "A" "B" "C"
    "1" 2010-09-29 23:59:59 0.0191961424604022 216 216
    "2" 2010-09-29 23:59:59 0.0191961424604022 216 216
    "3" 2010-09-29 23:59:59 0.0191961424604022 216 216
    "4" 2010-09-29 23:59:59 0.0191961424604022 216 216
    "5" 2010-09-29 23:59:59 0.0191961424604022 216 216

Upvotes: 1

Views: 132

Answers (1)

MattV
MattV

Reputation: 1383

It might be the fact that you're writing to the file outside of the loop. Try to append to the file inside of the loop as follows:

library("ncdf")
a <-list.files("D:\\Cloud\\Dropbox\\Documents\\Shared\\", "*", full.names = TRUE)

dt <- as.POSIXct(strptime(basename(a), "data_%Y%m%dT%H%M%S_%Y%m%dT%H%M%S", tz = "GMT"))
for(i in 1:length(a)){
  f <- open.ncdf(a[i])
  A = get.var.ncdf(nc=f,varid="Sgf",verbose=TRUE)
  B <- get.var.ncdf(nc=f,varid="gh")
  C <- get.var.ncdf(nc=f,varid="jk")
  df <- data.frame(date = dt, A, B ,C ) 
  print(df) # For debugging purposes
  if (i==1) {
     write.table(df,file="es55.txt")
     }
  else {
     write.table(df,file="es55.txt", append = TRUE)          
}

Otherwise, what is the output of the print(df) statement in each loop run?

Upvotes: 2

Related Questions