| 任务 |
计算4个样例到鸢尾花iris数据集上各个样例的距离（曼哈顿距离、欧氏距离、切比雪夫距离）：[4.8, 3.3, 1.5, 0.3],[5.6, 2.9, 3.5, 1.3], [6.8, 3.2, 4.6, 1.4], [6.9, 3.1, 5.2, 2.3] |
| Python |
import numpy as np;
from scipy.spatial.distance import cityblock, euclidean, chebyshev;
from sklearn.datasets import load_iris;
# 加载鸢尾花数据集
iris = load_iris();
# 获取鸢尾花数据集的数据
X = iris.data;
# 定义要计算距离的四个样例
samples = [[4.8, 3.3, 1.5, 0.3], [5.6, 2.9, 3.5, 1.3], [6.8, 3.2, 4.6, 1.4], [6.9, 3.1, 5.2, 2.3]];
# 使用for循环计算每个样例到鸢尾花数据集上各个样例的曼哈顿距离、欧氏距离和切比雪夫距离
for sample in samples:
manhattan_distances = [cityblock(sample, x) for x in X]; #左侧缩进4个空格
euclidean_distances = [euclidean(sample, x) for x in X]; #左侧缩进4个空格
chebyshev_distances = [chebyshev(sample, x) for x in X]; #左侧缩进4个空格
print(f"Sample: {sample}"); #左侧缩进4个空格
print(f"Manhattan distances: {manhattan_distances}"); #左侧缩进4个空格
print(f"Euclidean distances: {euclidean_distances}"); #左侧缩进4个空格
print(f"Chebyshev distances: {chebyshev_distances}"); #左侧缩进4个空格
print("===" * 20); #左侧缩进4个空格 |
| Python |
自己编写Python函数来计算距离（未调用库函数）
任务：计算x1（2，3）和点x2（3，5）之间的距离。
import numpy as np
x1 = np.array([2,3])
x2 = np.array([3,5])
# 直接用公式计算欧氏距离
dist1 = np.sqrt(np.sum((x1-x2)**2))
# 使用内置范数函数计算欧氏距离
dist2 = np.linalg.norm(x1 - x2, 2)
print(f"d1={dist1},d2={dist2}\n")
# 曼哈顿距离
dist3 = np.sum(np.abs(x1-x2))
print(f"d3={dist3}\n")
# 切比雪夫距离（练习自定义函数方式计算）
def q_distance(x1,x2): return abs(x1-x2).max(); #自定义函数
print(q_distance(x1,x2)) #进行函数调用 |
| C++ |
#include "orsci.h"
#include "orsci_dm.h"
using namespace orsci;
using namespace dm;
mdouble X = dmt::dataset::iris::iris_X();
mdouble A = "[4.8, 3.3, 1.5, 0.3]; [5.6, 2.9, 3.5, 1.3]; [6.8, 3.2, 4.6, 1.4]; [6.9, 3.1, 5.2, 2.3];";
for (int k = 0; k < A.rowCount(); k++)
{
rowdouble v = A.row(k);
vdouble cityblock;
vdouble euclid;
vdouble chebyshev;
for (int tt = 0; tt < X.rowCount(); tt++)
{
cityblock.push_back(X.row(tt).dist_manhattan(v));
euclid.push_back(X.row(tt).dist_euclid(v));
chebyshev.push_back(X.row(tt).dist_chebyshev(v));
}
cout << "当前向量：" << v << endl;
cout << "曼哈顿距离：" << cityblock << endl;
cout << "欧氏距离：" << euclid << endl;
cout << "切比雪夫距离：" << chebyshev << endl;
}
|