doc/maps.dox
author alpar
Wed, 05 May 2004 08:36:00 +0000
changeset 533 04eb0d9022c8
parent 289 98adf9276de0
child 685 c7e37b066033
permissions -rw-r--r--
Minor bugfix.
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/*!
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\page maps How to write your own maps
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\section read-maps Readable Maps
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The readable maps are very frequently used as the input of the
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algorithms.  For this purpose the most straightforward is to use the
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maps provided by Hugo's graph structres. Very often however, it is more
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convenient and/or more efficient to write your own readable map.
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You can find some example below.
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This simple map assigns \f$\pi\f$ to each edge.
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\code
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struct MyMap 
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{
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  typedef double ValueType;
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  double operator[](Graph::Edge e) const { return M_PI;}
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};
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\endcode
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An alternative way to define maps. For this, \c MapBase seems to
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be a better name then \c NullMap
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\code
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struct MyMap : public MapBase<Edge,double>
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{
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  double operator[](Graph::Edge e) const { return M_PI;}
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};
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\endcode
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Or, if we had \c KeyType and \c ValueType
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\code
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struct MyMap : public MapBase<Edge,double>
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{
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  ValueType operator[](KeyType e) const { return M_PI;}
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};
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\endcode
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Here is a more complex example. It provides a length function which is obtained
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from a base length function modified by a potential difference.
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\code
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class MyLengthMap 
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{
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  const Graph::EdgeMap &ol;
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  const Graph::NodeMap &pot;
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public:
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  typedef double ValueType;
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  double operator[](Graph::Edge e) const {
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    return ol.get(e)-pot.get(v)-pot.get(u);
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  }
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  MyComplexMap(const Graph::EdgeMap &o,const Graph::NodeMap &p) :
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    ol(o), pot(p);
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};
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\endcode
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\todo Please improve on the english. 
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\todo Don't we need \e to \e require a 'typedef xxx KeyType' tag, as well?
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*/