sample_lines: Read in random lines from a text file
In djvanderlaan/LaF: Fast Access to Large ASCII Files

Description Usage Arguments Details Value See Also Examples

Read in random lines from a text file

1	sample_lines(filename, n, nlines = NULL)

`filename`	character containing the filename of the file from which the lines should be read.
`n`	The number of lines that should be sampled from the file.
`nlines`	The total number of lines in the file. If not specified or `NULL` the number of lines is first determined using `determine_nlines`.

When nlines is not specified, the total number of lines is first determined. This can take quite some time. Therefore, specifying the number of lines can cause a significant speed up. It can also be used to sample lines from the first nlines line by specifying a value for nlines that is smaller than the number of lines in the file.

Returns a character vector with the sampled lines.

See readLines to read in all lines a text file; get_lines can be used to read in specified lines.

# Create temporary filename
tmpcsv  <- tempfile(fileext="csv")

writeLines(letters[1:20], con=tmpcsv)
sample_lines(tmpcsv, 10)

# Cleanup
file.remove(tmpcsv)