NAME

Tie::Hash::Interpolate - tied mathematical interpolation/extrapolation

VERSION

Version 0.07

SYNOPSIS

   use Tie::Hash::Interpolate;

   ## use tie interface

   tie my %lut, 'Tie::Hash::Interpolate', extrapolate => 'linear';

   $lut{3} = 4;
   $lut{5} = 6;

   print $lut{4};    ## prints 5
   print $lut{6.5};  ## prints 7.5

   ## or constructor interface

   my $lut = Tie::Hash::Interpolate->new( extrapolate => 'linear' );

   $lut->{3} = 4;
   $lut->{5} = 6;

   print $lut->{4};    ## prints 5
   print $lut->{6.5};  ## prints 7.5

DESCRIPTION

Tie::Hash::Interpolate provides a mechanism for using a hash as a lookup table for interpolated and extrapolated values.

Hashes can either be tied using the tie builtin or by constructing one with the new() method.

After your hash is tied (NOTE: key-value pairs added prior to the tie will be ignored), insert your known key-value pairs. If you then fetch a key that does not exist, an interpolation or extrapolation will be performed as necessary. If you fetch a key that does exist, the value stored for that key will be returned.

FUNCTIONS

new

OPTIONS

Options can be passed to tie after the Tie::Hash::Interpolate name is given, or directly to new() as key-value pairs.

   tie my %lut, 'Tie::Hash::Interpolate', extrapolate => 'fatal';

   ## or

   my $lut = Tie::Hash::Interpolate->new( one_key => 'constant' );

extrapolate

This option controls the behavior of the tied hash when a key is requested outside the range of known keys. Valid extrapolate values include:

• linear (default)

  extrapolate linearly based on the two nearest points

• constant

  keep the nearest value constant rather than extrapolating

• fatal

  throw a fatal exception

• undef

  return undef

one_key

This option controls the behavior of the tied hash when a key is requested and only one key exists in the hash. Valid one_key values include:

• fatal (default)

  throw a fatal exception

• constant

  all fetches return the one value that exists

• undef

  return undef

TO DO

- support multiple dimensions

- support autovivification of tied hashes

- set a per-instance mode for insertion or lookup

- be smarter (proximity based direction) about searching when doing interpolation

AUTHOR

Daniel B. Boorstein, <danboo@cpan.org>

COPYRIGHT AND LICENSE

Copyright 2004 by Daniel B. Boorstein

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.