The data i've got output was not yet what i expected. So to debug, i've sorted the data en printed it 

@$points = sort { $a->[3] <=> $b->[3] } @$points;
foreach (@$points) {
  print " $_->[3] $_->[0] $_->[1] $_->[2] \n";
}

[download]

gives me 

 1338020418 33.514447422 9.142337666 16.479736  
 1338020431 33.514425964 9.142852650 16.960449  
 1338020431 33.514425964 9.142852650 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020459 33.514211388 9.144140110 16.479736  
 1338020479 33.514125557 9.145019875 14.557007  
 1338020479 33.514125557 9.145019875 14.557007  
 1338020484 33.514104099 9.145234451 14.557007  
 1338020484 33.514104099 9.145234451 14.557007

[download]

and yes...there are duplicates. that need to be eliminated. I added the following 

my @unique = uniq @$points;

[download]

but then my data is gone, only empty fields are printed. That is a good and fast way to delete duplicates in data ???

In reply to What is the fastest way to delete duplicates from multi dimensional array ? by geogpx

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