Did anyone ever mention the 'countLines' function in R.utils. On Sun, Feb 26, 2012 at 5:55 PM, Hans Ekbrand <[email protected]> wrote: > > On Sun, Feb 26, 2012 at 09:39:46AM -0800, Rui Barradas wrote: > > Hello, > > > > > The first step before to create a loop row-by-row is to know > > > how many rows there are in the txt file without load in R to save > > > memory > > > problem. > > > > > > some people know the specific function? > > > > > > > I don't believe there's a specific function. > > As stated, OP does not need to know the number of lines in the file to > solve the problem. However, if you want to know that, I'd suggest the > command wc rather than writing a function in R to accomplish this. > > wc is also part of GNU coreutils > > $ wc -l foo.csv > 1138200 foo.csv > > > If you want to know how many rows are there in a txt file, try this > > function. > > > > numTextFileLines <- function(filename, header=FALSE, sep=",", > > nrows=5000){ > > tc <- file(filename, open="rt") > > on.exit(close(tc)) > > if(header){ > > # cnames: column names (not used) > > cnames <- read.table(file=tc, sep=sep, nrows=1, > > stringsAsFactors=FALSE) > > # cnames <- as.character(cnames) > > } > > n <- 0 > > while(TRUE){ > > x <- tryCatch(read.table(file=tc, sep=sep, nrows=nrows), > > error=function(e) > > e) > > if (any(grepl("no lines available", unclass(x)))) > > break > > if(nrow(x) < nrows){ > > n <- n + nrow(x) > > break > > } > > n <- n + nrows > > } > > n > > } > > But hey, programming R is fun, so why not? > > -- > Hans Ekbrand > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
-- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? Tell me what you want to do, not how you want to do it. ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
