Also, one thing to watch for in any plotting code is holes in the polygons. I don't think the Tiger data have holes

Ooooo they do.. found that pdf about 9 hours before you mentioned it. Im dealing with them now, at a huge cost, maybe more later.

Ill live with unzipped dirs for now, and look closer into "seek"ing on a zip file and into the format of a raw shp file. to see if my sequential reader would work for sequential access.

My cheap zip sequencer 

package cheap::zipbyline; 
use strict;
use warnings;
use Exporter;

  use Archive::Zip qw( :ERROR_CODES :CONSTANTS );

our @ISA= qw( Exporter );

# these CAN be exported.
our @EXPORT_OK = qw( zipbyline_start zipbyline_read zipbyline_close
                   );

# these are exported by default.
our @EXPORT = qw( );
my %zbl; 


sub zipbyline_start { 
  my $zf=shift; 
  my $mf=shift; 

    my $zip = Archive::Zip->new();
    unless ( $zip->read( $zf ) == AZ_OK ) { die 'read error';} 


    my ( $member, $status, $bufferRef );
    $member = $zip->memberNamed( $mf );
    $member->desiredCompressionMethod( COMPRESSION_STORED );
    $status = $member->rewindData();
    die "error $status" unless $status == AZ_OK;
    $zbl{$member}='';
    return $member; 
} # zbl start 


sub zipbyline_read { 
  my $member=shift; 
    my ( $status, $bufferRef );
    my $nl=index($zbl{$member},"\n"); 
    while ( ( $nl == -1) && ! $member->readIsDone() ) {
      ( $bufferRef, $status ) = $member->readChunk(1000);
      die "error $status"
                if $status != AZ_OK && $status != AZ_STREAM_END;
      # do something with $bufferRef:
      $zbl{$member}.=$$bufferRef; 
      $nl=index($zbl{$member},"\n"); 
    } # while 
if ($nl == -1 ) {$zbl{$member}=undef; return $zbl{$member};} 
my $line=substr($zbl{$member},0,$nl+1); 
$zbl{$member}=substr($zbl{$member},$nl+1); 
return $line; 
} #  zbl 

sub zipbyline_close { 
  my $member=shift; 
  delete $zbl{$member}; 
 } # zbl close

[download]
This will probably get improvements so i can read 2 files out of the same zip at the same time without doing two my $zip=new ... $zip->read($zf) sets, havent needed it yet.

In reply to Re^4: Geo::ShapeFile memory problem by huck
in thread Geo::ShapeFile memory problem by rhzhang

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