Perl line/delimiter file formatting syntax - perl

Question

I'm trying to figure out how to use a code that's written in perl, but am not very familiar with perl syntax. I was wondering if someone could tell me what the format of the file #metafilecache is? The code is failing to read the samplerate within the file, but I'm not sure how I have it formatted incorrectly. Here's the excerpt of the code I think is appropriate:
my $tnet = $ARGV[0];
my $tsta = $ARGV[1];
my $stadir = $ARGV[2];
if ( ! -d "$targetdir" ) {
mkdir "$targetdir" || die "Cannot create $targetdir: $?\n";
}
die "Cannot find PDF bin base dir: $pdfbinbase\n" if ( ! -d "$pdfbinbase" );
my %targetdays = ();
my %targetchan = ();
# Collect target files in the $pdfbinbase dir, limited by $changlob
foreach my $nsldir (glob("$pdfbinbase/{CHRYS}/$tnet.$tsta.*")) {
next if ( ! -d "$nsldir" ); # Limit to directories
# Extract location ID from directory name
my ($net,$sta,$loc) = $nsldir =~ /\/(\w+)\.(\w+)\.([\w-]+)$/;
if ( $net ne $tnet ) {
print "Target network ($tnet) != network ($net)\n";
next;
}
if ( $sta ne $tsta ) {
print "Target station ($tsta) != station ($sta)\n";
next;
}
foreach my $chandir (glob("$nsldir/$changlob")) {
next if ( ! -d "$chandir" ); # Limit to directories
# Extract channel code from directory name
my ($chan) = $chandir =~ /.*\/([\w\d]+)$/;
foreach my $yeardir (glob("$chandir/Y*")) {
next if ( ! -d "$yeardir" ); # Limit to directories
# Extract year from directory name
my ($year) = $yeardir =~ /^.*\/Y(\d{4,4})$/;
foreach my $daybin (glob("$yeardir/D*.bin")) {
next if ( ! -f "$daybin" ); # Limit to regular files
my ($day) = $daybin =~ /^.*\/D(\d{3,3})\.bin$/;
$targetdays{"$loc.$chan.$year.$day"} = $daybin;
$targetchan{"$loc.$chan"} = 1;
}
}
}
}
if ( $verbose > 1 ) {
print "Target days from PDF bin files:\n";
my $count = 0;
foreach my $tday (sort keys %targetdays) {
print "Target day: $tday => $targetdays{$tday}\n";
$count++;
}
print "Targets: $count\n";
}
# Remove targets that have already been calculated by checking
# results files against targets.
foreach my $tchan ( keys %targetchan ) {
my ($loc,$chan) = split (/\./, $tchan);
# Generate target file name
my $targetfile = undef;
if ( $loc ne "--" ) { $targetfile = "$targetdir/$prefix-$loc.$chan"; }
else { $targetfile = "$targetdir/$prefix-$chan"; }
print "\nChecking target file for previous results: $targetfile\n"
if ( $verbose );
next if ( ! -f "$targetfile" );
# Open result file and remove any targets that are included
open IN, "$targetfile" || next;
foreach my $line (<IN>) {
next if ( $line =~ /^YEAR\.DAY/ );
my ($year,$day) = $line =~ /^(\d+).(\d+)/;
# Delete this target
delete $targetdays{"$loc.$chan.$year.$day"};
}
close IN;
}
if ( $verbose > 1 ) {
print "Remaining target days:\n";
my $count = 0;
foreach my $tday (sort keys %targetdays) {
print "Target day: $tday => $targetdays{$tday}\n";
$count++;
}
print "Remaining Targets: $count\n";
}
my %targetfiles = ();
# Calculate and store PDF mode for each target day
TARGET: foreach my $tday (sort keys %targetdays) {
my ($loc,$chan,$year,$day) = split (/\./, $tday);
my %power = ();
my %count = ();
my #period = ();
# Determine sampling rate
my $samprate = GetSampRate ($tnet,$tsta,$loc,$chan);
print "Samplerate for $tnet $tsta $loc $chan is: $samprate\n" if (
$verbose );
if ( ! defined $samprate ) {
if ( ($tsta eq "ECSD") || ($tsta eq "SFJ") || ($tsta eq "CASEE") ||
($tsta eq "JSC") ){
next;
}
else {
print "Cannot determine sample rate for channel
$tnet.$tsta.$loc.$chan\n";
next;
}
}
This is the subroutine GetSampRate:
sub GetSampRate { # GetSampRate (net,sta,loc,chan)
my $net = shift;
my $sta = shift;
my $loc = shift;
my $chan = shift;
my $samprate = undef;
# Generate source name: Net_Sta_Loc_Chan
my $srcname = "${net}_${sta}_";
$srcname .= ($loc eq "--") ? "_" : "${loc}_";
$srcname .= "$chan";
if ( $#metafilecache < 0 ) {
my $metafile = "$stadir/metadata.txt";
if ( ! -f "$metafile" ) {
print "GetSampRate(): Cannot find metadata file: $metafile\n";
return undef;
}
# Open metadata file
if ( ! (open MF, "<$metafile") ) {
print "GetSampRate(): Cannot open: $metafile\n";
return undef;
}
# Read all lines in the metafilecache
#metafilecache = <MF>;
close MF;
}
# Read all lines starting with srcname into #lines
my #lines = grep { /^$srcname/ } #metafilecache;
# Find maximum of sample rates for this channel
foreach my $line ( #lines ) {
my #fields = split(/\t/, $line);
my $rate = $fields[7];
$samprate = $rate if (!defined $samprate || $rate > $samprate);
}
return $samprate;
}

Answer 1

The code you have shown is very clunky.
As far this scope is concerned, the file is called $stadir/metadata.txt and I can't help with $stadir as it's either undefined or a global value that is set elsewhere — not a great design idea
After that, #metafilecache = <MF> loads the entire file into the array #metafilecache, leaving a trailing newline character at the end of each element
Then my #lines = grep { /^$srcname/ } #metafilecache duplicates to #lines all lines beginning with the string held in $srcname. This is another global variable that shouldn't be used
The following for loop splits the line on tab ("\t" or "\x09") separators and sets $rate to the eighth value ($fields[7]). $samprate is updated at each iteration if the latest value of $rate is greater than the current stored maximum
I hope that helps