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

Description Usage Arguments Value Author(s) See Also Examples

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

1	grep_system(pattern, filename, options = "")

`pattern`	`character` to search
`filename`	`character` file name
`options`	`character` passed to `grep`

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)
   grep_system("Tom", filename)
   grep_system("Dick", filename)
   grep_system("harry", filename, options="-i")

   unlink(filename)