cut_system: Use system 'cut' (*NIX only)
In tharte/tutils: Tom's UTILity functionS

Description Usage Arguments Value Author(s) See Also Examples

Use system cut (*NIX only). For large files this is much faster than reading the file into R and cutting the columns.

1	cut_system(cols, filename, sep = "\|")

`cols`	`integer` `vector` index of columns to cut
`filename`	`character` file name
`sep`	`character` delimiter (passed to `cut`)

character vector output from cut

Thomas P. Harte

system, cut

tab<- read.csv(text='Name,Age,Salary,ID
            Dick,38,32k,1
            Tom,21,21k,2
            Harry,56,NA,3',
            header=TRUE,
            stringsAsFactors=FALSE
   )
   for (col in which(col_classes(tab)=="character"))
       tab[, col]<- tutils::trim(tab[, col])
   tab

   filename<- paste(tempfile(), ".csv", sep="")
   write.csv(tab, file=filename, row.names=FALSE, quote=FALSE)
   cut_system(1, filename, sep=",")
   cut_system(4, filename, sep=",")
   cut_system(c(1,4), filename, sep=",")
   unlink(filename)