n.readLines {reader}

Read 'n' lines (ignoring comments and header) from a file.

Description

Useful when you don't know the length/structure of a file and want a useful sample to look at. Can skip ahead in the file too. Copes well when there are less than 'n' lines in the file.

Usage

n.readLines(fn, n, comment = "#", skip = 0, header = TRUE)

Arguments

fn

name of the file(s) to get the length of

n

number of valid lines to attempt to read looks at the top few lines (ignoring comments)

comment

a comment symbol to ignore lines in files

skip

number of lines to skip at top of file before processing

header

whether to allow for, and skip, a header row

Value

returns the first n lines of the file meeting the criteria, or if 'skip' implies lines beyond the length of the file, the result,will be truncated - although in this case, the last line will always be read.

Author(s)

Nicholas Cooper [e-mail]

Examples

orig.dir <- getwd(); setwd(tempdir()); # move to temporary dir
dat <- matrix(sample(100),nrow=10)
write.table(dat,"temp.txt",col.names=FALSE,row.names=FALSE)
n.readLines("temp.txt",n=2,skip=2,header=FALSE)
dat[3:4,]
unlink("temp.txt")
setwd(orig.dir) # reset working directory to original