10.25

Posted 2021-01-15 zhangjij

import numpy as np

x = np.random.randint(1,50,[20,1])

y = np.zeros(20)

k = 3

def initcenter(x,k):

    return x[:k]

 

kc = initcenter(x,k)

kc

def nearest(kc,i):

    d=(abs(kc-i))

    w=np.where(d==np.min(d))

    return w[0][0]

 

kc = initcenter(x,k)

nearest(kc,93)

def xclassify(x,y,kc):

    for i in range(x.shape[0]):

        y[i] = nearest(kc,x[i])

    return y

 

kc = initcenter(x,k)

y = xclassify(x,y,kc)

print(kc,y)

def kcmean(x,y,kc,k):

    l = list(kc)

    flag = False

    for c in range(k):

        m = np.where(y == c)

        n = np.mean(x[m])

        if l[c] != n:

            l[c] = n

            flag = True

            print(l,flag)

    return (np.array(l),flag)

 

kc = initcenter(x,k)

flag = True

k = 3

 

 

while flag:

    y = xclassify(x,y,kc)

    kc,flag = kcmean(x,y,kc,k) 

 

2鸢尾花花瓣长度数据做聚类并用散点图显示

#鸢尾花花瓣长度数据做聚类并用散点图显示。
import numpy as np
from sklearn.datasets import load_iris    
iris = load_iris()
x = iris.data[:,2]
y = np.zeros(150)
 
def initcenter(x,k):    #初始聚类中心数组
    return x[:k]
 
def nearest(kc,i):       #数组中的值，与聚类中心最小距离所在类别的索引号
    d = (abs(kc-i))
    w = np.where(d == np.min(d))
    return w[0][0]
 
def xclassify(x,y,kc):
    for i in range(x.shape[0]):       #对数组的每个值进行分类，shape[0]读取矩阵第一维度的长度
        y[i] = nearest(kc,x[i])
    return y
 
def kcmean(x,y,kc,k):     #计算各聚类新均值
    l = list(kc)
    flag = False
    for c in range(k):
        print(c)
        m = np.where(y == c)
        if len(m) == 1:
            n = x[c]
        else:
            n=np.mean(x[m])
        if l[c] != n:
            l[c] = n
            flag = True     #聚类中心发生变化
            print(l,flag)
    return (np.array(l),flag)
 
 
k = 3
kc = initcenter(x,k)
 
flag = True
print(x,y,kc,flag)
 
#判断聚类中心和目标函数的值是否发生改变，若不变，则输出结果，若改变，则返回2
while flag:
    y = xclassify(x,y,kc)
    kc, flag = kcmean(x,y,kc,k)
    print(y,kc,type(kc))
     
print(x,y)
import matplotlib.pyplot as plt
plt.scatter(x,x,c=y,s=50,cmap="Paired");
plt.show()

　　

 

 

 

3.用sklearn.cluster.KMeans，鸢尾花花瓣长度数据做聚类并用散点图显示.

from sklearn.cluster import KMeans
import numpy as np
from sklearn.datasets import load_iris
import matplotlib.pyplot as plt
data = load_iris()
iris = data.data
petal_len = iris[:,2:3]
print(petal_len)
k_means = KMeans(n_clusters=3) #三个聚类中心
result = k_means.fit(petal_len) #Kmeans自动分类
kc = result.cluster_centers_ #自动分类后的聚类中心
y_means = k_means.predict(petal_len) #预测Y值
plt.scatter(petal_len,np.linspace(1,150,150),c=y_means,marker=‘x‘)
plt.show()

　　

 

4.鸢尾花完整数据做聚类并用散点图显示.

from sklearn.cluster import KMeans
import numpy as np
from sklearn.datasets import load_iris
import matplotlib.pyplot as plt
data = load_iris()
iris = data.data
petal_len = iris
print(petal_len)
k_means = KMeans(n_clusters=3) #三个聚类中心
result = k_means.fit(petal_len) #Kmeans自动分类
kc = result.cluster_centers_ #自动分类后的聚类中心
y_means = k_means.predict(petal_len) #预测Y值
plt.scatter(petal_len[:,0],petal_len[:,2],c=y_means,marker=‘x‘)
plt.show()