78 lines
1.6 KiB
C++
78 lines
1.6 KiB
C++
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// ProbabDistrib.h
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// Declares the cProbabDistrib class representing a discrete probability distribution curve and random generator
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/*
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Usage:
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1, Create a cProbabDistrib instance
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2, Initialize the distribution either programmatically, using the SetPoints() function, or using a definition string
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3, Ask for random numbers in that probability distribution using the Random() function
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*/
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#pragma once
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#include "FastRandom.h"
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class cProbabDistrib
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{
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public:
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class cPoint
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{
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public:
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int m_Value;
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int m_Probability;
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cPoint(int a_Value, int a_Probability) :
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m_Value(a_Value),
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m_Probability(a_Probability)
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{
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}
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} ;
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typedef std::vector<cPoint> cPoints;
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cProbabDistrib(int a_MaxValue);
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/** Sets the distribution curve using an array of [value, probability] points, linearly interpolated. a_Points must not be empty. */
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void SetPoints(const cPoints & a_Points);
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/** Sets the distribution curve using a definition string; returns true on successful parse */
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bool SetDefString(const AString & a_DefString);
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/** Gets a random value from a_Rand, shapes it into the distribution curve and returns the value. */
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int Random(MTRand & a_Rand) const;
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/** Maps value in range [0, m_Sum] into the range [0, m_MaxValue] using the stored probability */
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int MapValue(int a_OrigValue) const;
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int GetSum(void) const { return m_Sum; }
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protected:
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int m_MaxValue;
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/** Cumulative probability of the values, sorted, for fast bsearch lookup */
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cPoints m_Cumulative;
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/** Sum of all the probabilities across all values in the domain; -1 if not set */
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int m_Sum;
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} ;
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