## The module "real2index" of the Mastrave modelling library

**Daniele de Rigo**

#### Copyright and license notice of the function real2index

Copyright © 2005,2006,2007,2008,2009,2010 Daniele de Rigo

The file real2index.m is part of Mastrave.

Mastrave is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Mastrave is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Mastrave. If not, see http://www.gnu.org/licenses/.

#### Function declaration

[indices,cardinality,glossary] = real2index(reals,mode= 'ascending' )

#### Description

Floating point values cannot be used as indices.
@real2index maps floating point numbers into positive integers
preserving their order.
In case of sparse matrices, the mapping replaces only nonzeros.
If ` reals ` is a cell-array of matrices then

`is returned as a cell-array whose elements are the corresponding matrices of indices. Each index of`

**indices**`represents a value of (the elements of)`

**indices**`which may occur several times in`

**reals**`. To each occurrence of the same value corresponds the same index. The set of these correspondences is returned in the vector`

**reals**`, whose length is the`

**glossary**`of the indices set. The particular way in which indices are generates can be governed using the optional`

**cardinality**`input argument (if omitted, its default value is 'ascending').`

**mode**In case some element of ` reals ` is a string, it is considered as a
matrix of characters each of them is converted in its ASCII numerical code.
If you need to consider strings as atomic elements to which associate
single indices (instead of associating an index for each character composing
a given string), you could consider to use instead @cellstr2index .

#### Input arguments

realsMatrix of real numbers or cell array whose elements are matrices of real numbers.::cellnumeric-1|cellnumeric-2::modeCriterion for generating indices from::string::. (Default: 'ascending'). Valid modes are: mode │ meaning ──────────────┼───────────────────────────────── 'ascending' │ Indices are generated by │ associating to each element of │realsthe position of its │ first occurrence in the set of │realselements sorted in │ ascending order. ──────────────┼───────────────────────────────── 'descending' │ Indices are generated by │ associating to each element of │realsthe position of its │ first occurrence in the set of │realselements sorted in │ descending order. ──────────────┼───────────────────────────────── 'forward' │ Indices are generated by │ associating to each element of │realsthe position of its │ first occurrence in the set of │realselements. ──────────────┼───────────────────────────────── 'backward' │ Indices are generated by │ associating to each element of │realsthe position of its │ first occurrence in the set of │realselements listed │ in reverse order. ──────────────┼───────────────────────────────── 'random' │ Indices are generated by │ associating to each element of │realsthe position of its │ first occurrence in the set of │realselements randomly │ shuffled.reals

#### Example of usage

% Basic usage (strings are considered ASCII integer matrices) m1 = '[ idx, n, gloss ] = real2index( reals )' m2 = randn(1,20) m3 = m2( ceil(rand(1,20)*20) ) m4 = zeros(3,2); m4(:) = m2(1:numel(m4)) m5 = zeros(5); m5(ceil(rand(1,numel(m4))*25)) = m4(:) m5 = sparse( m5 ) idx = real2index( m1 ) [idx, len] = real2index( {m1 , m2} ) [idx, len] = real2index( {m1 , m2 , m3} ) [idx, len] = real2index( {m1 , m2 , m4} ) [idx, len] = real2index( {m1 , m2 , m5} ) [idx, len] = real2index( {m4 , m5} ) [idx, len] = real2index( m5 ) [idx, len, g] = real2index( m2 ) m2_rep = zeros(size(m2)); m2_rep(:) = g(idx) [idx, len, g] = real2index( m1 ) m1_rep = char( zeros(size(m1)) ); m1_rep(:) = char( g(idx) ) % Howaffects the generated indices idx = real2index( m3 , 'ascending' ) idx = real2index( m3 , 'descending' ) idx = real2index( m3 , 'forward' ) idx = real2index( m3 , 'backward' ) idx = real2index( m3 , 'random' ) idx = real2index( m3 , 'random' )mode

See also: sortable2index, cellstr2index, cell2sparse Keywords: conversion, cell-array, real, indices Version: 0.7.2

#### Support

The Mastrave modelling library is committed to provide reusable and general - but also robust and scalable - modules for research modellers dealing with computational science. You can help the Mastrave project by providing feedbacks on unexpected behaviours of this module. Despite all efforts, all of us - either developers or users - (should) know that errors are unavoidable. However, the free software paradigm successfully highlights that scientific knowledge freedom also implies an impressive opportunity for collectively evolve the tools and ideas upon which our daily work is based. Reporting a problem that you found using Mastrave may help the developer team to find a possible bug. Please, be aware that Mastrave is entirely based on voluntary efforts: in order for your help to be as effective as possible, please read carefully the section on reporting problems. Thank you for your collaboration.