DATA MINING
Desktop Survival Guide by Graham Williams |
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Folders and Files |
> getwd() # Identify the current default working directory > setwd("h:/work/") # Change the current default working directory > file.exists("filename") # Returns TRUE if the file exists > unlink("filename") # Deletes the file or directory > fname <- file.choose() # An interactive file chooser. > choose.dir() # > dir <- tclvalue(tkchooseDirectory()) # GUI which requires library(tcltk). |
List files in a folder in the order by modification time:
> lst <- file.info(dir()) > lst[order(lst$mtime),] |
MS/Windows paths use the backward slash to separate components. This
is a problem since the backslash is used as a standard mechanism for
introducing special characters within strings. Thus, R requires a
double back slash or will seamlessly allow the use of the forward slash.
A useful utility on a MS/Windows environment, where backslashes are
used in paths, and R likes to have forward slashes, is the
following (Duncan Golicher, 5 Jan 2006, r-help):
setwd.clip <- function() { options(warn=-1) setwd(gsub("\\\\", "/",readLines("clipboard"))) options(warn=0) getwd() } |
> dir <- setwd.clip() |
R packages supply files and we can access them in a installation independent way using system.file:
> system.file("csv", "audit.csv", package = "rattle") |
[1] "/usr/local/lib/R/site-library/rattle/csv/audit.csv" |
We can view the contents of files in R using file.show:
> file.show(system.file("csv", "audit.csv", package = "rattle")) |