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基础概念
关于匈牙利算法的基础概念就不作具体描述了,不清楚的可以自己搜索相关知识
主要需要了解的知识点
- 二分图
- 匹配:最大匹配,完美匹配
- 路径:交错路径,增广路径
算法核心:通过不断寻找增广路径找到最大匹配的道路
算法实现
1. 使用线性规划库scipy
默认取最小组合,设置maximize为True时取最大组合
import numpy as np
from scipy.optimize import linear_sum_assignmenta = np.array([[84, 65, 3, 34], [65, 56, 23, 35], [63, 18, 35, 12]])
row, col = linear_sum_assignment(a)
print("行坐标:", row, "列坐标:", col, "最小组合:", a[row, col])
row, col = linear_sum_assignment(a, True)
print("行坐标:", row, "列坐标:", col, "最大组合:", a[row, col])
输出
行坐标: [0 1 2] 列坐标: [2 3 1] 最小组合: [ 3 35 18]
行坐标: [0 1 2] 列坐标: [0 1 2] 最大组合: [84 56 35]
2. 使用munkres库
源码:https://github.com/bmc/munkres
文档:http://software.clapper.org/munkres/
目前该库已经可以使用pip install munkres安装
默认是取最小组合,需要取最大组合则使用make_cost_matrix转换数据矩阵
import numpy as np
from munkres import Munkres, make_cost_matrix, DISALLOWEDa = np.array([[84, 65, 3, 34], [65, 56, 23, 35], [63, 18, 35, 12]])
b = make_cost_matrix(a, lambda cost: (a.max() - cost) if (cost != DISALLOWED) else DISALLOWED)mk = Munkres()
# 最小组合
indexes = mk.compute(a.copy()) # 会改变输入的源数据
print("最小组合:",indexes, a[[i[0] for i in indexes], [i[1] for i in indexes]])
# 最大组合
indexes = mk.compute(b)
print("最大组合:", indexes, a[[i[0] for i in indexes], [i[1] for i in indexes]])
输出
最小组合:[(0, 2), (1, 3), (2, 1)] [ 3 35 18]
最大组合:[(0, 0), (1, 1), (2, 2)] [84 56 35]
注意使用np.array输入,mk.compute会改变输入的源数据
3. KM算法python实现
基本思想:通过引入顶标,将最优权值匹配转化为最大匹配问题
参考:
https://blog.csdn.net/u010510549/article/details/91350549
https://www.cnblogs.com/fzl194/p/8848061.html
实现了矩阵的自动补0和最大最小组合计算
import numpy as npclass KM:def __init__(self):self.matrix = Noneself.max_weight = 0self.row, self.col = 0, 0 # 源数据行列self.size = 0 # 方阵大小self.lx = None # 左侧权值self.ly = None # 右侧权值self.match = None # 匹配结果self.slack = None # 边权和顶标最小的差值self.visx = None # 左侧是否加入增广路self.visy = None # 右侧是否加入增广路# 调整数据def pad_matrix(self, min):if min:max = self.matrix.max() + 1self.matrix = max-self.matrixif self.row > self.col: # 行大于列,添加列self.matrix = np.c_[self.matrix, np.array([[0] * (self.row - self.col)] * self.row)]elif self.col > self.row: # 列大于行,添加行self.matrix = np.r_[self.matrix, np.array([[0] * self.col] * (self.col - self.row))]def reset_slack(self):self.slack.fill(self.max_weight + 1)def reset_vis(self):self.visx.fill(False)self.visy.fill(False)def find_path(self, x):self.visx[x] = Truefor y in range(self.size):if self.visy[y]:continuetmp_delta = self.lx[x] + self.ly[y] - self.matrix[x][y]if tmp_delta == 0:self.visy[y] = Trueif self.match[y] == -1 or self.find_path(self.match[y]):self.match[y] = xreturn Trueelif self.slack[y] > tmp_delta:self.slack[y] = tmp_deltareturn Falsedef km_cal(self):for x in range(self.size):self.reset_slack()while True:self.reset_vis()if self.find_path(x):breakelse: # update slackdelta = self.slack[~self.visy].min()self.lx[self.visx] -= deltaself.ly[self.visy] += deltaself.slack[~self.visy] -= deltadef compute(self, datas, min=False):""":param datas: 权值矩阵:param min: 是否取最小组合,默认最大组合:return: 输出行对应的结果位置"""self.matrix = np.array(datas) if not isinstance(datas, np.ndarray) else datasself.max_weight = self.matrix.sum()self.row, self.col = self.matrix.shape # 源数据行列self.size = max(self.row, self.col)self.pad_matrix(min)print(self.matrix)self.lx = self.matrix.max(1)self.ly = np.array([0] * self.size, dtype=int)self.match = np.array([-1] * self.size, dtype=int)self.slack = np.array([0] * self.size, dtype=int)self.visx = np.array([False] * self.size, dtype=bool)self.visy = np.array([False] * self.size, dtype=bool)self.km_cal()match = [i[0] for i in sorted(enumerate(self.match), key=lambda x: x[1])]result = []for i in range(self.row):result.append((i, match[i] if match[i] < self.col else -1)) # 没有对应的值给-1return resultif __name__ == '__main__':a = np.array([[84, 65, 3, 34], [65, 56, 23, 35], [63, 18, 35, 12]])# a = np.array([[84, 65], [3, 34], [63, 18], [35, 12]])km = KM()min_ = km.compute(a.copy(), True)print("最小组合:", min_, a[[i[0] for i in min_], [i[1] for i in min_]])max_ = km.compute(a.copy())print("最大组合:", max_, a[[i[0] for i in max_], [i[1] for i in max_]])
输出:
最小组合: [(0, 2), (1, 3), (2, 1)] [ 3 35 18]
最大组合: [(0, 0), (1, 1), (2, 2)] [84 56 35]
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