Eri*_*rik 3 java algorithm distance histogram
我正在寻找计算两个直方图之间的地球移动器距离(EMD)的 java代码(或库).这可以是直接或间接的(例如使用匈牙利算法).我在c/c ++中找到了几个这样的实现(例如"Fast and Robust Earth Mover的距离",但我想知道是否有一个现成的Java版本.
我将使用EMD计算来评估本文在我正在研究的科学项目中给出的方法.
更新
使用各种资源,我估计下面的代码应该可以解决问题.determineMinCostAssignment是匈牙利算法确定的最优分配的计算.为此,我将使用http://konstantinosnedas.com/dev/soft/munkres.htm中的代码. 我主要关注的是计算流程:我不确定这是否正确.是否有人可以验证这是否正确？
/**
* Determines the Earth Mover's Distance between two histogram assuming an equal distance between two buckets of a histogram. The distance between
* two buckets is equal to the differences in the indexes of the buckets.
*
* @param threshold
* The maximum distance to use between two buckets.
*/
public static double determineEarthMoversDistance(double[] histogram1, double[] histogram2, int threshold) {
if (histogram1.length != histogram2.length)
throw new InvalidParameterException("Each histogram must have the same number of elements");
double[][] groundDistances = new double[histogram1.length][histogram2.length];
for (int i = 0; i < histogram1.length; ++i) {
for (int j = 0; j < histogram2.length; ++j) {
int abs_diff = Math.abs(i - j);
groundDistances[i][j] = Math.min(abs_diff, threshold);
}
}
int[][] assignment = determineMinCostAssignment(groundDistances);
double costSum = 0, flowSum = 0;
for (int i = 0; i < assignment.length; i++) {
double cost = groundDistances[assignment[i][0]][assignment[i][1]];
double flow = histogram2[assignment[i][1]];
costSum += cost * flow;
flowSum += flow;
}
return costSum / flowSum;
}