http://users.softlab.ntua.gr/~ttsiod/gnuplotStreaming.html

diff --git a/driveGnuPlots.pl b/driveGnuPlots.pl
new file mode 100755 (executable)
index 0000000..cfe0b3c
--- /dev/null
+++ b/driveGnuPlots.pl
@@ -0,0 +1,136 @@
+#!/usr/bin/perl -w
+use strict;
+
+sub usage {
+    print "Usage: $0 <options>\n";
+    print <<OEF;
+where options are (in order):
+
+  NumberOfStreams                         How many streams to plot (windows)
+  Stream1_WindowSampleSize <Stream2...>   This many window samples for each stream
+  Stream1_Title <Stream2_Title> ...       Title used for each stream
+  (Optional) Stream1_geometry <Stream2_geometry>...  X and Y position in pixels from the top left
+
+The last parameters (the optionally provided geometries of the gnuplot windows) 
+are of the form: 
+  WIDTHxHEIGHT+XOFF+YOFF
+OEF
+    exit(1);
+}
+
+sub Arg {
+    if ($#ARGV < $_[0]) {
+       print "Expected parameter missing...\n\n";
+       usage;
+    }
+    $ARGV[int($_[0])];
+}
+
+sub main {
+    my $argIdx = 0;
+    my $numberOfStreams = Arg($argIdx++);
+    print "Will display $numberOfStreams Streams (in $numberOfStreams windows)...\n";
+    my @sampleSizes;
+    for(my $i=0; $i<$numberOfStreams; $i++) {
+       my $samples = Arg($argIdx++);
+       push @sampleSizes, $samples;
+       print "Stream ".($i+1)." will use a window of $samples samples\n";
+    }
+    my @titles;
+    for(my $i=0; $i<$numberOfStreams; $i++) {
+       my $title = Arg($argIdx++);
+       push @titles, $title;
+       print "Stream ".($i+1)." will use a title of '$title'\n";
+    }
+    my @geometries;
+    if ($#ARGV >= $argIdx) {
+       for(my $i=0; $i<$numberOfStreams; $i++) {
+           my $geometry = Arg($argIdx++);
+           push @geometries, $geometry;
+           print "Stream ".($i+1)." will use a geometry of '$geometry'\n";
+       }
+    }
+    my $terminal = "";
+    open GNUPLOT_TERM, "echo 'show terminal;' | gnuplot 2>&1 |";
+    while (<GNUPLOT_TERM>) {
+       if (m/terminal type is (\w+)/) {
+           $terminal=$1;
+       }
+    }
+    close GNUPLOT_TERM;
+
+    # unfortunately, the wxt terminal type does not support positioning. 
+    # hardcode it...
+    $terminal  = "x11";
+
+    my @gnuplots;
+    my @buffers;
+    my @xcounters;
+    shift @ARGV; # number of streams
+    for(my $i=0; $i<$numberOfStreams; $i++) {
+       shift @ARGV; # sample size
+       shift @ARGV; # title
+       shift @ARGV; # geometry
+       local *PIPE;
+       my $geometry = "";
+       if (-1 != $#geometries) {
+           $geometry = " -geometry ".$geometries[$i];
+       }
+       open PIPE, "|gnuplot $geometry " || die "Can't initialize gnuplot number ".($i+1)."\n";
+       select((select(PIPE), $| = 1)[0]);
+       push @gnuplots, *PIPE;
+       print PIPE "set xtics\n";
+       print PIPE "set ytics\n";
+       print PIPE "set style data linespoints\n";
+       print PIPE "set grid\n";
+       if ($numberOfStreams == 1) {
+           print PIPE "set terminal $terminal title '".$titles[0]."' noraise\n";
+       } else {
+           print PIPE "set terminal $terminal noraise\n";
+       }
+       print PIPE "set autoscale\n";
+       my @data = [];
+       push @buffers, @data;
+       push @xcounters, 0;
+    }
+    my $streamIdx = 0;
+    select((select(STDOUT), $| = 1)[0]);
+    while(<>) {
+       chomp;
+       my @parts = split /:/;
+       $streamIdx = $parts[0];
+       my $buf = $buffers[$streamIdx];
+       my $pip = $gnuplots[$streamIdx];
+       my $xcounter = $xcounters[$streamIdx];
+       my $title = $titles[$streamIdx];
+
+       # data buffering (up to stream sample size)
+       push @{$buf}, $parts[1];
+       #print "stream $streamIdx: ";
+       print $pip "set xrange [".($xcounter-$sampleSizes[$streamIdx]).":".($xcounter+1)."]\n";
+       if ($numberOfStreams == 1) {
+           print $pip "plot \"-\"\n";
+       } else {
+           print $pip "plot \"-\" title '$title'\n";
+       }
+       my $cnt = 0;
+       for my $elem (reverse @{$buf}) {
+           #print " ".$elem;
+           print $pip ($xcounter-$cnt)." ".$elem."\n";
+           $cnt += 1;
+       }
+       #print "\n";
+       print $pip "e\n";
+       if ($cnt>=$sampleSizes[$streamIdx]) {
+           shift @{$buf};
+       }
+       $xcounters[$streamIdx]++;
+    }
+    for(my $i=0; $i<$numberOfStreams; $i++) {
+       my $pip = $gnuplots[$i];
+       print $pip "exit;\n";
+       close $pip;
+    }
+}
+
+main;