#! perl -slw
use strict;
use List::Util qw[ sum ];
use Data::Dump qw[ pp ];

our $X //= 10;
our $Y //= 10;

my @xs = map -3+rand 6, 1 .. $X;
my @ys = map -3+rand 6, 1 .. $Y;

my %bins;

for my $x ( @xs ) {
    my $xc = ( int( $x * 10 )  + 0.5 ) / 10;
    for my $y ( @ys ) {
        my $yc = ( int( $y * 10 ) + 0.5 ) / 10;
        ++$bins{ "$xc:$yc" };
    }
}

pp \%bins;

printf "Buckets used: %d, total values %d \n",
    scalar keys %bins, sum values %bins;

##</code><code>##

c:\test>824030 -X=10 -Y=10
{
  "-0.15:-0.55" => 2,
  "-0.15:-1.25" => 1,
  "-0.15:-2.15" => 1,
  "-0.15:-2.25" => 1,
  "-0.15:-2.35" => 1,
  "-0.15:-2.45" => 1,
  "-0.15:-2.55" => 1,
  "-0.15:0.05"  => 1,
  "-0.15:2.05"  => 1,
  "-1.15:-0.55" => 2,
  "-1.15:-1.25" => 1,
  "-1.15:-2.15" => 1,
  "-1.15:-2.25" => 1,
  "-1.15:-2.35" => 1,
  "-1.15:-2.45" => 1,
  "-1.15:-2.55" => 1,
  "-1.15:0.05"  => 1,
  "-1.15:2.05"  => 1,
  "-1.65:-0.55" => 2,
  "-1.65:-1.25" => 1,
  "-1.65:-2.15" => 1,
  "-1.65:-2.25" => 1,
  "-1.65:-2.35" => 1,
  "-1.65:-2.45" => 1,
  "-1.65:-2.55" => 1,
  "-1.65:0.05"  => 1,
  "-1.65:2.05"  => 1,
  "-1.75:-0.55" => 4,
  "-1.75:-1.25" => 2,
  "-1.75:-2.15" => 2,
  "-1.75:-2.25" => 2,
  "-1.75:-2.35" => 2,
  "-1.75:-2.45" => 2,
  "-1.75:-2.55" => 2,
  "-1.75:0.05"  => 2,
  "-1.75:2.05"  => 2,
  "-2.55:-0.55" => 2,
  "-2.55:-1.25" => 1,
  "-2.55:-2.15" => 1,
  "-2.55:-2.25" => 1,
  "-2.55:-2.35" => 1,
  "-2.55:-2.45" => 1,
  "-2.55:-2.55" => 1,
  "-2.55:0.05"  => 1,
  "-2.55:2.05"  => 1,
  "-2.65:-0.55" => 2,
  "-2.65:-1.25" => 1,
  "-2.65:-2.15" => 1,
  "-2.65:-2.25" => 1,
  "-2.65:-2.35" => 1,
  "-2.65:-2.45" => 1,
  "-2.65:-2.55" => 1,
  "-2.65:0.05"  => 1,
  "-2.65:2.05"  => 1,
  "0.05:-0.55"  => 2,
  "0.05:-1.25"  => 1,
  "0.05:-2.15"  => 1,
  "0.05:-2.25"  => 1,
  "0.05:-2.35"  => 1,
  "0.05:-2.45"  => 1,
  "0.05:-2.55"  => 1,
  "0.05:0.05"   => 1,
  "0.05:2.05"   => 1,
  "0.25:-0.55"  => 2,
  "0.25:-1.25"  => 1,
  "0.25:-2.15"  => 1,
  "0.25:-2.25"  => 1,
  "0.25:-2.35"  => 1,
  "0.25:-2.45"  => 1,
  "0.25:-2.55"  => 1,
  "0.25:0.05"   => 1,
  "0.25:2.05"   => 1,
  "2.95:-0.55"  => 2,
  "2.95:-1.25"  => 1,
  "2.95:-2.15"  => 1,
  "2.95:-2.25"  => 1,
  "2.95:-2.35"  => 1,
  "2.95:-2.45"  => 1,
  "2.95:-2.55"  => 1,
  "2.95:0.05"   => 1,
  "2.95:2.05"   => 1,
}

Buckets used: 81, total values 100