Being able to read right from one of these zip files without needing to unzip it to disk first would be a treat, but i realize it maybe a little too much to ask for.

In that kind of mode requiring me to read it sequentially would be no problem, i'd expect that kind of processing to be kinda common ie 


  my $dir0='h:/active/tiger_data';
  my $sfips='42'; # pa 


# make $base->{$blockid10}{color} via 
# zipbyline reads a zip member sequentially 
#   as in http://search.cpan.org/~phred/Archive-Zip-1.59/lib/Archive/Z
+ip.pm#Low-level_member_data_reading 
#  my $sn=$fips2state->{$sfips}.'2010.sf1'; 
#  my $zf=$dir0.'/sf1/'.$sn.'.zip';
#  my $mf=$fips2state->{$fips}.'geo2010.sf1'; ; 
#  my $member=zipbyline_start($zf,$mf); 
#  while (my $line=zipbyline_read($member)){ 
#    ... pull out datums AREALAND AREAWATR POP100, create density 
#    } # line   
#  zipbyline_close($member); 
# sort by density, total POP100, 
#   break into deciles, 
#   assign a decile color to each $base->{$blockid10}{color}

  my $dir=$dir0.'/shapes';
  my $state='tabblock2010_'.$sfips.'_pophu';
  my $shapefn=$dir.'/'.$state.'/'.$state;
  my $imgfn=$dir0.'/gifs/'.$state.'.gif'; 

  # this points to the unzipped dir now,
  # be nice to just point to $dir.'/'.$state.'.zip' instead 
  my $sf = Geo::ShapeFile->new ($shapefn); 
  $sf->caching(shp                => 0); 
  $sf->caching(dbf                => 0); 
  $sf->caching(shx                => 0); 
  $sf->caching(shapes_in_area     => 0); 

  my $x_min=$sf->x_min(); 
  my $x_max=$sf->x_max(); 
  my $y_max=90-$sf->y_min(); # need to invert 90 is top 0 is bot 
  my $y_min=90-$sf->y_max(); 
  my $totalblocks = $sf->shapes();
#   $totalblocks=5000; 


  my $xsize=$x_max-$x_min; 
  my $ysize=$y_max-$y_min; 

  my $imgy=5000; 
  my $yscale=$imgy/$ysize; 


  my $pfx=-0.00923452628555483*($sf->y_min)+ 1.15467278754118; # proje
+ction factor 


  my $imgx=$yscale*$xsize*$pfx;
  my $xscale=$imgx/($xsize); 

  sub xproj { return (($_[0])-($x_min))*$xscale; } 
  sub yproj { return ((90-$_[0])-$y_min)*$yscale; } 

  # create a new image
  my $im = new GD::Image($imgx+1,$imgy+1);

  for my $si (1 .. $totalblocks) {
    my %attr = $sf->get_dbf_record($si);
    my $blockid10 = $attr{BLOCKID10};
    my $color=$base->{$blockid10}{color}; 
    unless ($color) {$color=$yellow;}
    my $polygon = $sf->get_shp_record($si);
     for my $pi (1 .. $polygon->num_parts) {
        my $part = $polygon->get_part($pi);
        my $poly = new GD::Polygon;
        for my $hash (@$part){ 
          $poly->addPt(xproj($hash->{X}),yproj($hash->{Y}));
          } 
        my $first=$part->[0]; 
        my $last =$part->[-1]; 
        if ($first->{X} ne $last->{X} || $first->{Y} ne $last->{Y} ) {
+ 
          $poly->addPt(xproj($first->{X}),yproj($first->{Y}));
          } 
        $im->filledPolygon($poly,$color);
        } # pi
    }  # si

  outlines (); 

  open (my $img,'>',$imgfn); binmode $img;print $img $im->gif;close $i
+mg;
  exit; 

sub outlines { 
  my $state='tl_2010_'.$sfips.'_county10';
  my $shapefn=$dir.'/'.$state.'/'.$state;
# this too points at an unzipped dir, 
# be nice to point at $dir.'/'.$state.'.zip' instead 
  my $sf = Geo::ShapeFile->new ($shapefn); 
  $sf->caching(shp                => 0); 
  $sf->caching(dbf                => 0); 
  $sf->caching(shx                => 0); 
  $sf->caching(shapes_in_area     => 0); 
  my $totalblocks = $sf->shapes();
  for my $si (1 .. $totalblocks) {
    my $polygon = $sf->get_shp_record($si);
    for my $pi (1 .. $polygon->num_parts) {
        my $part = $polygon->get_part($pi);
        my $poly = new GD::Polygon;
        for my $hash (@$part){ 
          $poly->addPt(xproj($hash->{X}),yproj($hash->{Y}));
          } 
        my $first=$part->[0]; 
        my $last =$part->[-1]; 
        if ($first->{X} ne $last->{X} || $first->{Y} ne $last->{Y} ) {
+ 
          $poly->addPt(xproj($first->{X}),yproj($first->{Y}));
          } 
        $im->openPolygon($poly,$black);
        } # pi
    }  # si 

  }

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PA output at this sendspace link while it lasts
MO output at this sendspace link while it lasts

In reply to Re^2: Geo::ShapeFile memory problem by huck
in thread Geo::ShapeFile memory problem by rhzhang

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