Hi,

I've been trying to solve this challenge for quite awhile, now I'm hoping a Perl expert out there has an elegant solution.

I build an array of hashes from a database table, calculating mileage distance as I insert each record into the structure. Then I sort the array of hashes to come up with the records that have the smallest distance from each client. each tutor has multiple records tied to them thru their ID, but I only want the closest record associated with each. The rest I want to remove from the structure.

In the example below, I only want one of tutor ID 24 and one of ID 50 to show up in the final result.

I'm assuming there may be some way to do this within the sort line I use below, but everything I've tried so far hasn't worked.

Here are my inputs, outputs and code snippets: (thanks in advance for anyone's help!)


Database records:

ID, tutorID, Latitude, Longitude, City, State, Zipcode 
1, 24, 39.948927, -75.1586630, Philadelphia, Pennsylvania, 19107
2, 24, 44.813947, -93.9194250, Young America, Minnesota, 55555
3, 24, 34.270548, -119.217135, Ventura, California, 93003
5,  6, 35.938033, -78.1193720, Spring Hope, North Carolina, 27882
6, 50, 32.357439, -111.044532, Tucson, Arizona, 85741
7,  5, 41.299209, -96.0521530, Omaha, Nebraska, 68134
8, 50, 38.921460, -119.117640, Yerington, Nevada, 89447
9,  7, 40.798205, -73.7382850, Great Neck, New York, 11027



################## Perl code snippet ######################

$i=0;

$sql = qq|select ID, tutorID, Latitude, Longitude, City, State, Zipcod
+e from $table_tzips where Zipcode IS not NULL|;
$sth = $dbh->prepare($sql);
$sth->execute();
$tzips = $sth->fetchrow_hashref();
while (defined $tzips) {

    $trdist = &calculate_distance($clong, $clat, $tzips->{Longitude}, 
+$tzips->{Latitude});
    
    ($tutorsdata[$i]{trID},
     $tutorsdata[$i]{tutorsID},
     $tutorsdata[$i]{tmiles},
     $tutorsdata[$i]{city},
     $tutorsdata[$i]{state},
     $tutorsdata[$i]{zipcode}) =
     
    ($tzips->{ID},
     $tzips->{tutorID},
     $trdist,
     $tzips->{City},
     $tzips->{State},
     $tzips->{Zipcode});

     $i++;

    $tzips=$sth->fetchrow_hashref();
}
$sth->finish;


@sortthetutors = sort{ $$a{tmiles} <=> $$b{tmiles} } @tutorsdata;

print "Tutor Distances:\n\n";

for $printtutors(@sortthetutors) {

print "$$printtutors{trID}, 
    $$printtutors{tutorsID}, 
    $$printtutors{tmiles}, 
    $$printtutors{city}, 
    $$printtutors{state}, 
    $$printtutors{zipcode} \n";
}


################## END Perl code snippet ######################


Current output of this:

3, 24, 0, Ventura, California, 93003
8, 50, 321, Yerington, Nevada, 89447
6, 50, 489, Tucson, Arizona, 85741
7,  5, 1348, Omaha, Nebraska, 68134
2, 24, 1522, Young America, Minnesota, 55555
5,  6, 2307, Spring Hope, North Carolina, 27882
1, 24, 2432, Philadelphia, Pennsylvania, 19107
9,  7, 2502, Great Neck, New York, 11027

Desired output:

3, 24, 0, Ventura, California, 93003
8, 50, 321, Yerington, Nevada, 89447
7,  5, 1348, Omaha, Nebraska, 68134
5,  6, 2307, Spring Hope, North Carolina, 27882
9,  7, 2502, Great Neck, New York, 11027

[download]

Again, thanks!

In reply to sorting an array of hashes and removing duplicates by jmfees

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