Piping stdin to R

This does not happen if you explicitly open the stdin connection.

#!/usr/bin/env Rscriptf <- file("stdin")open(f)while(length(line <- readLines(f,n=1)) > 0) {  write(line, stderr())  # process line}

Jeff and I wrote littler to do just this (and a few other things). Because of littler, I never looked that closely at Rscript -- but this should in principle work just fine.

Here is one of our early examples, using output from /bin/ls (and a quick filter by awk) to summarize file size:

edd@max:~/svn/littler/examples$ ls -l /boot/ | \                                    awk '!/^total/ {print $5}' | ./fsizes.r     Min.  1st Qu.   Median     Mean  3rd Qu.     Max.       24   130300   730700  3336000  4527000 14670000   The decimal point is 6 digit(s) to the right of the |   0 | 0000000000000011111111122777777777   2 | 777777777   4 | 555577777   6 |    8 |   10 |   12 | 5  14 | 24466677edd@max:~/svn/littler/examples$ 

Here the script fsizes.r is just three lines:

edd@max:~/svn/littler/examples$ cat fsizes.r #!/usr/bin/r -ifsizes <- as.integer(readLines())print(summary(fsizes))stem(fsizes)edd@max:~/svn/littler/examples$ 

This is the easiest I've found (assuming numeric input):

x <- scan(file("stdin")

you can test it with:

$ echo -e "1\n2\n3" | R -s -e 'x <- scan(file("stdin")); summary(x)'Read 3 items   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.     1.0     1.5     2.0     2.0     2.5     3.0