Prints the first nrows lines of the sum stats.
preview(path, nrows = 5L, nThread = 1L)Path to local file or remote URL. Alternatively, can pass in a data.frame to be used directly.
The maximum number of rows to read. Unlike read.table, you do not need to set this to an estimate of the number of rows in the file for better speed because that is already automatically determined by fread almost instantly using the large sample of lines. nrows=0 returns the column names and typed empty columns determined by the large sample; useful for a dry run of a large file or to quickly check format consistency of a set of files before starting to read any of them.
The number of threads to use. Experiment to see what works best for your data on your hardware.
No return