infomeasure.c

来自「vc的源代码程序的基于最小特征向量的元素的集合方法的程序源代码」· C语言 代码 · 共 34 行

#include "infoMeasure.h"

float plogp(float P)
{
	if(P<0.0000001) return 0; // assume it is ZERO

//	cout << "P=" << P <<";";
	return P*log(P)/log(2.0);
}

float entropy (int MaxClass, int *CntV, int Cnt)
{
	float v=0;
	
	for(int k=0; k<MaxClass; k++)
	{
		v += plogp((float)CntV[k]/Cnt);
//		cout << CntV[k] <<"/"<<Cnt<< "="<<(float)CntV[k]/Cnt<<"|";
	}

	return -v;
}

float infoMeasure(int MaxClass, int *leftCntV, int *rightCntV,
  int leftCnt, int rightCnt, int total)  // total = leftCnt+rightCnt
{
	// the division to total can be ignored, as it
	// will not
	// affact the comparing reslts. 
	return( (entropy(MaxClass, leftCntV, leftCnt)*leftCnt 
		+ entropy(MaxClass, rightCntV, rightCnt)*rightCnt)/total);
}