Sort Results Numerically - brief 
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 Sort Results Numerically - brief

Quote:

> Could someone help me sort these results numerically?

> I have found a sort routine:

> The problem is, I wish to sort by a calculated value $distance, which is
> done for each record.
> I want to sort my results numerically according to the $distance for each
> result.


> record),
> but NOT the actual Fields of the records in the datafile.

> Can anyone help?

[ some code deleted ]

Quote:


>            ##### possible location for numerical sorting

>            {&display}
> }

Errhm, you want to do the numerical sorting _before_ the loop, like so:


$field[3] }




                &display;
        }

This can be a bit slow, since you'd be splitting records quite a lot.

It's more efficient to just compute the distance once and remember it.
This trick is known as the "Schwartzian Transform", after Randal L. Schwartz.


$field[3]; }




In fact, it's even more efficient to split each record just once, when
it's read in,
and work with split records from then on:

        open(DATA, "$Folder/data.txt") or die "Can't read $Folder/data.txt: $!\n";
        while (<DATA>) {

                my $distance = $field[4] - $field[3];

                ## rejects any record with value $distance over 50

        }
        close DATA;

        print "$Header1\n";


                print " No matches\n";
        } else {


                        print " Company: $ad->[6], City: $ad->[2], ",
                                        "State: $ad->[3], Distance: $ad->[0]<HR>\n";
                }
        }

        print "$Footer1\n";
        exit;

Hope this helps,

-- HansM



Fri, 29 Aug 2003 09:55:15 GMT  
 
 [ 1 post ] 

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