在简单的R脚本中收到“在1级没有这样的索引”错误

Question

When I run the following block of R code:

require(openair)
require(png)

topDir <- "C:/Users/djh/Desktop/WindRoses"
subdirs <- c("Abbotsford_Observations") #, "Vancouver_Observations", "Abbotsford_Modelled", "Vancouver_Modelled")
years <- c(1985) #, 1995, 2001, 2006)

for(i in 1:length(subdirs)){
  for(j in 1:length(years)){
    wd <- paste(topDir, subdirs[i], years[j], sep="/")
    files <- list.files(wd, pattern = "\\.out$")
    for(k in 1:length(files)){
      theData <- data.frame(read.table(paste(wd, files[k], sep="/"), header = TRUE, sep=""))
      u <- theData$U10
      v <- theData$V10

      theData["windSpd"] <- sqrt(u^2 + v^2)
      theData["windDir"] <- (270 - (atan2(u/theData$windSpd, v/theData$windSpd)*(180/pi)))

      nameSplit <- strsplit(files[k], ".")

      png(file=paste(wd, "/", nameSplit[[1]], ".png", sep = ""))
      windRose <- windRose(theData, theData$windSpd, theData$windDir, angle = 22.5)
      dev.off()
    }
  }
}

I receive the error:

"Error in .subset2(x, i, exact = exact) : no such index at level 1" after the entire code has been run

Looking at other instances of this error on stack exchange, it seems it might be linked to the string splitting of files[k] , but none of the answers have solved my problem.

Note: I have tried to use unlist on nameSplit and it did not solve the problem.

An example of the strings I am trying to split is:

wrfout_d04_1985-07-16.ts.abbotsford.out

Is this definitely where the error is occurring or is there an obvious cause elsewhere in the script?

Answer 1

I think that in the regex definition that you use to split the file names the dot should be masked by a double backslash, as it is done in the line where the files variable is assigned. Additionally, an unlist() command might be useful if afterwards you want to select the first part of the split string with nameSplit[1] .

I therefore suggest that you use

nameSplit <- unlist(strsplit(files[k], "\\."))

and see if the problem persists.

Hope this helps.

Answer 2

The issue was coming from a different line actually. The windRose command from the openair package requires wind speed and direction to be entered as they are in the following line, rather than how they appear in the original question.

wind_rose <- windRose(theData, ws="windSpd", wd="windDir", angle = 22.5)