#! perl -sw
use strict;

#! The rounding may need some correction.
sub Xtoix{ int($_[0]/(1066+2/3)+.5) } #! the closest approximate mapping functions
sub Ytoiy{ int($_[0]/( 933+1/3)+.5) } #! I could derive from your limited sample data.

my @grid;

open GRIDS, 'yourgridsfile' or die $!;
while(<GRIDS>) {
	#! Isolate the data
	my ($map, $grid, $subgrid, $x0, $y0, $x1, $y1 ) =  split ',';
	my $ix = Xtoix( $x0 ); #! map to 0 based indexes
	my $iy = Ytoiy( $y0 );
	#! build and store a hash with the data into the grid.
	$grid[$ix][$iy] = 
        {map=>$map, grid=>$grid, subgrid=>$subgrid, x0=>$x0, y0=>$y0, x1=>$x1, y1=>$y1 };
}
close GRIDS;

open PLACES, 'yourplacefilename' or die $!;
while(<PLACES>) {
	my ($thingy, $x, $y)= split ','; # Forgot to split!!
	my $ix = Xtoix( $x );
	my $iy = Ytoiy( $y );
	my $adjusted = 0;
	my $gridref = $grid[$ix][$iy];
	++$adjusted, $ix-- if $x < $gridref->{x0};
	++$adjusted, $ix++ if $x > $gridref->{x1};
	++$adjusted, $iy-- if $y < $gridref->{y0};
	++$adjusted, $iy++ if $y > $gridref->{y1};
	$gridref = $grid[$ix][$iy] if $adjusted;
	print $thingy, ' is on map ', $gridref->{map},
				   ' at grid ',   $gridref->{grid},
				   ' subgrid ',   $gridref->{subgrid},
}
close PLACES;