diff --git a/tsfilter b/tsfilter
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index 0000000..5e872da
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+++ b/tsfilter
@@ -0,0 +1,99 @@
+#!/usr/bin/perl -w 
+use strict;
+use TimeSeries;
+use Getopt::Long;
+use Pod::Usage;
+use POSIX qw(strftime);
+
+=head1 NAME
+
+tsfilter - filter a time series in column format
+
+=head1 SYNOPSIS
+
+tsfilter
+[--start time]
+[--end time ]
+[--time_t]
+[--tsv]
+[file ...]
+
+=head1 DESCRIPTION
+
+...
+
+The --time_t option specifies that the timestamps are in seconds since
+the epoch. Otherwise they are parsed by add_timestring function (which
+in turn uses the parse_date function of the HTTP::Date module).
+
+=cut
+my $time_t =0;
+my $tsv   = 0;
+my $start;
+my $end;
+GetOptions('start=s' => \$start,
+	   'end=s'   => \$end,
+	   'time_t'  => \$time_t,
+	   'tsv'     => \$tsv,
+          ) 
+    or pod2usage(verbose => 0);
+
+my $sep = $tsv ? qr/\t/ : qr/\s+/;
+
+if (defined $start) {
+    if ($start =~ /^\d+$/) {
+	# already numeric
+    } elsif ($start =~ /^([-+]\d+)([dhms])$/) {
+	$start = time() + $1 * ($2 eq 'd' ? 86400 : $2 eq 'h' ? 3600 : $2 eq 'm' ? 60 : 1);
+    } else {
+	$start = str2time($start);
+    }
+} else {
+    $start = '-Inf';
+}
+
+if (defined $end) {
+    if ($end =~ /^\d+$/) {
+	# already numeric
+    } elsif ($end =~ /^([-+]\d+)([dhms])$/) {
+	$end = time() + $1 * ($2 eq 'd' ? 86400 : $2 eq 'h' ? 3600 : $2 eq 'm' ? 60 : 1);
+    } else {
+	$end = str2time($end);
+    }
+} else {
+    $end = 'Inf';
+}
+
+binmode STDOUT, ':raw';
+
+my $ts = TimeSeries->new();
+while (<>) {
+    chomp;
+    my @legend = split($sep);
+    shift @legend;	# first must be for timestamp
+    $ts->legend(@legend);
+    last;
+}
+while (<>) {
+    chomp;
+    my ($timestamp, @values) = split($sep);
+    if ($time_t) {
+	$ts->add($timestamp, @values);
+    } else {
+	$ts->add_timestring($timestamp, @values);
+    }
+}
+print join("\t", "date", $ts->legend), "\n";
+for my $dp (@{ $ts->{data} }) {
+    if ($dp->[0] >= $start && $dp->[0] <= $end) {
+	if ($time_t) {
+	    print $dp->[0];
+	} else {
+	    print strftime("%Y-%m-%dT%H:%M:%S%z", localtime($dp->[0]));
+	}
+	for my $v (@{$dp->[1]}) {
+	    print "\t$v";
+	}
+	print "\n";
+    }
+}