comment on

my %distances = (
    452 => 'London',
    678 => 'Paris',
    890 => 'Rome',
);
[download]

> would it be possible to get the value Paris by looking up the non existent key of 672?

Sure, add the non-existent key 672 pointing to Paris as nearest neighbor! :)

Seriously, a one kilometer grid of distances on earth only means precalculating at most 20000 entries (but better use an array then).

You can also go for a compromise and add a wider grid to the hash, like e.g. 10 kilometers. (The optimal width depends on your data).

Now rounding 672 to 670 and 680 will lead you to precalculated hash entries pointing to Paris. Can't be much faster...

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.