我尝试根据网络上的某些示例编写和编辑代码,代码如下所示:
from math import sqrt# 计算两个向量之间的欧几里得距离def euclidean_distance(row1, row2): distance = 0.0 for i in range(len(row1)-1): distance += (row1[i] - row2[i])**2 return sqrt(distance)# 查找最接近的邻居def get_neighbors(train, test_row, num_neighbors): distances = list() for train_row in train: dist = euclidean_distance(test_row, train_row) distances.append((train_row, dist)) distances.sort(key=lambda tup: tup[1]) neighbors = list() for i in range(num_neighbors): neighbors.append(distances[i][0]) return neighbors# 测试距离函数dataset = [[2.7810836,2.550537003,0], [1.465489372,2.362125076,0], [3.396561688,4.400293529,0], [1.38807019,1.850220317,0], [3.06407232,3.005305973,0], [7.627531214,2.759262235,1], [5.332441248,2.088626775,1], [6.922596716,1.77106367,1], [8.675418651,-0.242068655,1], [7.673756466,3.508563011,1]]neighbors = get_neighbors(dataset, dataset[0], 3)#set(dataset) & set(neighbors)#type(neighbors) is int#set(dataset).intersection(neighbors)for neighbor in neighbors: print(neighbor)
我想做的是:
- 获取3个最接近的邻居,
- 将这些最接近的邻居与’dataset’进行比较,
- 返回匹配的数据点的索引。
例如:从上面的代码中,结果是:
[2.7810836, 2.550537003, 0][3.06407232, 3.005305973, 0][1.465489372, 2.362125076, 0]
我希望得到的最终结果是:
result = [1, 5, 2]
这是从选定数据点(包括自身)开始的最近3个邻居在数据集中的索引,假设数据索引从1开始,而不是0。
回答:
你的代码中的错误是,你从get_neighbors函数中返回了行本身。要解决这个问题,请将这一行代码:
neighbors.append(distances[i][0])
更改为
neighbors.append(train.index(distances[i][0]) + 1)
这会找到行在完整行列表中的索引,并加1,因为你希望索引从1开始。
现在结果是
[1, 5, 2]