NAME
    Text::LookUpTable - Perl5 module for text based look up table operations

SYNOPSIS
      $tbl = Text::LookUpTable->load_file('my_table.tbl');
      $tbl = Text::LookUpTable->load($str_tbl);
      $tbl = Text::LookUpTable->build($x_size, $y_size, $x_title, $y_title);

      print $tbl;
      $str_tbl = "$tbl";

      $tbl->save_file();
      $tbl->save_file('my_table.tbl');

      $val = $tbl->get($x, $y);
      $tbl->set($x, $y, $val);

      @diff_coords = $tbl->diff($tbl2);
      $diffp = $tbl->diff($tbl2, 1);  # true/false no coordinates

      @xdiffs = $tb1->diff_x_coords($tb2);
      @ydiffs = $tb1->diff_y_coords($tb2);

      @x_coords = $tbl->get_x_coords();
      @y_coords = $tbl->get_y_coords();

      $res = $tbl->set_x_coords(@x_coords);
      $res = $tbl->set_y_coords(@y_coords);

      $str_plot = $tbl->as_plot('R');
      $str_plot = $tbl->as_plot('Maxima');
      print FILE $str_plot;

      $tbl_copy = $tbl->copy();

DESCRIPTION
    Text::LookUpTable provides operations for creating, storing, displaying,
    plotting, loading, and querying a *look up table* structure. The format
    of the stored structure is designed to be visually easy to understand so
    that it can be easily edited using a text editor.

    The authors inteded use of this library is to allow a user to edit a
    text file representation of a look up table which can then be loaded in
    to an embedded controller such as MegaSquirt [http://www.msextra.com].
    Additional code would be needed to convert this generic structure to
    whatever application specific format is required.

    What is a *look up table* and how is it different than a *table*? A
    *look up table* is commonly used in embedded controllers to avoid the
    use of costly floating pointing operations by looking up a value based
    on the input coordiantes. A function with two inputs (f(x, y)) which
    would use floating point operations can be represented (with some loss
    in precsion) as a table.

    In contrast a *table* (or spreadsheet) has any number of columns/rows.
    The columns can be of different types. And a table does not try to
    represent any sort of function, it just stores data.

STRING FORMAT
    The format of the look up table when stored to a string or file should
    look like the example below.

                            rpm
 
                  [1000]   [1500]  [2000]  [2500]
           [100]  14.0     15.5    16.4    17.9
      map  [90]   13.0     14.5    15.3    16.8
           [80]   12.0     13.5    14.2    15.7

    The x (across top) and y (left column) coordinates have their values
    enclosed in square brackets. All values must be present. And the titles
    can only span one line. There can be any number of lines and spaces as
    long as the values can be discerned. When saving and restoring a table
    the original spacing will not be preserved.

    The x values start at offset 0 at the left and increase towards the
    right. The y values start at offset 0 at the bottom and increase upward.

OPERATIONS
  Text::LookUpTable->load($string);
      Returns: a new table object on success, FALSE on error

    Creates a new look up table object by parsing the given string. See the
    section *STRING FORMAT* for details on format it expects.

    If you want to load a table from a *file* see *load_file*.

  Text::LookUpTable->load_file($file)
      Returns: new object on success, FALSE on error

    Works like *load* but obtains the text from the $file first.

    Stores the name of file so that save_file can be used without having to
    specify the file again.

  Text::LookUpTable->build($x_size, $y_size, $x_title, $y_title)
      Returns: new object on success, FALSE on error

    Creates a blank object with all values initialized to zero and
    dimensions of $x_size and $y_size.

  Text::LookUpTable->copy($obj)
      Returns: new object on success, FALSE on error

    Creates a new object as a copy of the given object.

  $tbl->as_string();
      Returns string on success, FALSE on error.

    Convert the object to a string representation.

    This operation is used to overload the string operation so the shorthand
    form can be used.

      print $tbl;         # print the object as a string

      $to_save = "$tbl";  # get the string format to be saved

    The long hand form $tbl->as_string(); should not normally be needed.

  $tbl->save_file($file);
      Returns TRUE on success, FALSE on error

    Optional argument $file, can specify the file to save to. If ommitted it
    will save to the last file that was used. If no last file is stored it
    will produce an error.

  $tbl->get_*_coords();
      Returns list of all x/y coordinates on success, FALSE on error

    Offset 0 for the X coordinates start at the LEFT of the displayed table
    and increases RIGHTWARD.

    Offset 0 for the Y coordinates start at the BOTTOM of the displayed
    table and increases UPWARD.

      @xs = $tbl->get_x_coords();
      @ys = $tbl->get_y_coords();

  $tbl->set_*_coords(@new_coords);
      Returns TRUE on success, FALSE on error

    Assigns the x/y coordinates to the values given in the list.

    The coordinates must be in ascending order so that lookup_points, etc
    will work correctly.

      $res = $tbl->set_x_coords(@new_x_coords);
      $res = $tbl->set_y_coords(@new_y_coords);

  $tbl->set($x, $y, $val);
      Returns TRUE on success OR FALSE on error

    Set the value to $val at the given $x and $y coordinate offset.

  $tbl->get($x, $y);
      Returns $value on success, FALSE on error

    Get the value at the given horizontal ($x) and vertical ($y) offset.

  $tbl->lookup_points($val_x, $val_y, $range);
      Returns @points (see below) on success, FALSE on error

    Lookup the points for the given values.

    The $range argument defines how far from the nearest point in the x and
    y direction the resulting set of points should include.

    Unlike offsets (see get()) which correspond to one point, a lookup based
    on values may correspond to multiple points of varying degrees (closer
    to some points than others).

    Suppose, for example, we are given the following map

                            rpm
 
                  [1000]   [1500]  [2000]  [2500] [3000]
           [100]  14.0     15.5    16.4    17.9    21.9
      map  [90]   13.0     14.5    15.3    16.8    21.9
           [80]   12.0     13.5    14.2    15.7    20.5
           [70]   12.0     13.5    14.2    15.7    20.1
           [60]   12.0     13.5    14.2    15.7    18.2

    A lookup of the x value of 2010 and a y value of 85 (notice the values
    do not correspond exactly) and a range of 1 would select the points
    shown below (show with an X).

     @points = $tbl->lookup_points(2010, 85, 1);

                            rpm
 
                  [1000]   [1500]  [2000]  [2500] [3000]
           [100]  14.0     15.5    16.4    17.9    21.9
      map  [90]   13.0     X       X       X       21.9
           [80]   12.0     X       X       X       20.5
           [70]   12.0     X       X       X       20.1
           [60]   12.0     13.5    14.2    15.7    18.2

    The set of points returned would be (in no particular order)

      ([1, 1], [1, 2], [1, 3], [2, 1], [2, 2], [2, 3], ...)

    And this set of points could then be used to retrieve and/or assign the
    range of values.

  $tb1->diff($tb2, $break);
      Returns TRUE if different, FALSE otherwise.

      If $break is FALSE it returns a list of positions that are different.

    Determines whether the VALUES two tables are different. Does not check
    if the coordinates or the titles are different.

    If $break is FALSE return a complete list of coordinates that are
    different. If $break is TRUE it breaks out and returns as soon it is
    found that they are different for a slight performance improvement.

  $tb1->diff_*_coords($tb2)
      Returns list of differences on success, FALSE on error

     @xdiffs = $tb1->diff_x_coords($tb2);
     @ydiffs = $tb1->diff_y_coords($tb2);

  $tbl->as_plot('plot type', [type specific args ...] );
      Returns: string on success, FALSE on error

    Convert the table to a representation suitable for plotting. The string
    may need to be output to a file depending on how the plotting program is
    called.

    See below for the various plot types.

   R  [www.r-project.org]
    The string can be output to a file and then the file can be sourced to
    produce a plot. It depends upon the rgl library
    [http://cran.r-project.org/web/packages/rgl/index.html].

     $tbl->as_plot('R');

     shell$ ./a.out > file.R
     shell$ R

     > source('file.R')

     (plot displayed)

   Maxima [maxima.sourceforge.net]
    Example usage using lutasplot.pl utility (in bin directory).

     shell$ lutasplot.pl veTable1 Maxima > veTable1.maxima 
     shell$ maxima
     (%i1) batch("veTable1.maxima");
        (..., plot output, etc)

PREREQUISITES
     Module                Version
     ------                -------
     Text::Aligner         0.03
     File::Slurp           9999.13
  
     The version numbers given have been tested and shown to work
     but other versions may work as well.

VERSION
    This document refers to Text::LookUpTable version 0.07.

REFERENCES
      [1]  MegaSquirt Engine Management System
           http://www.msextra.com

      [2]  R Project
           http://www.r-project.org

      [3]  rgl: 3D visualization device system (OpenGL)
           http://cran.r-project.org/web/packages/rgl/index.html

      [4]  Gnuplot
           http://www.gnuplot.info

      [5]  Maxima
           http://maxima.sourceforge.net

AUTHOR
        Jeremiah Mahler <jmmahler@gmail.com>
        CPAN ID: JERI
        https://plus.google.com/+JeremiahMahler/about

COPYRIGHT
    Copyright (c) 2014, Jeremiah Mahler. All Rights Reserved. This module is
    free software. It may be used, redistributed and/or modified under the
    same terms as Perl itself.