risks of using setwd() in a script?

Question

I\'ve heard it said that it is bad practice to use setwd() in a script.

• What are the risks/dangers associated with it?
• What are bett

Answer 1

I can't think of any particular issues with using setwd() in a script run on a server I manage as it does return an error which can be trapped with try(), and you can manage it. I have used setwd() when being lazy about paths - see below!

I use file.path() extensively in scripts production or otherwise. Working across the files in an input directory and putting the output graphics and reports elsewhere. So something along the lines of... (untested) This would be a bit tedious using setwd().

kInDir <- '~/Indir'
kOutDir <- '~/Outdir'
flist <- dir(path=kInDir, pattern='^[a-z]{2,5}\\.csv$')
# note I could have used full.names=T - but it's easier not to...
for (fnam in flist) {
  # full path to the report file created
  sfnam <- file.path(kOutDir, gsub('.csv', '_report.txt', fnam))
  # full path to the csv file that will be created
  ofnam <- file.path(kOutDir, gsub('.csv', '_b.csv', fnam))
  #
  # ok... we're going to process this CSV file...
  r1 <- read.csv(file.path(kInDir, fnam))
  #
  # we''ll put the output from the analysis into this report file
  sink(sfnam, split=TRUE)
  # processs it... into a new data.frame k1
  # blah blah blah...
  #
  write.csv(k1, file=ofnam, row.names=FALSE)
  sink() # turn off this particular report file
}