代码如下：

# -*- coding: utf-8 -*-
"""
Created on Fri May 11 10:26:58 2018

@author: eagle
"""

# =============================================================================
# 用K近邻预测Iris(鸢尾)数据集
# =============================================================================


from sklearn.datasets import load_iris
from sklearn.cross_validation import train_test_split
from sklearn.preprocessing import StandardScaler
from sklearn.neighbors import KNeighborsClassifier
from sklearn.metrics import classification_report

#导入数据集
iris = load_iris()
#print(iris.data.shape)  #（150，4）共150条数据，4个属性
#查看数据描述
#print(iris.DESCR)

#对数据集进行分割（训练数据、测试数据）
X_train,X_test,y_train,y_test = train_test_split(iris.data,iris.target,test_size=0.25,random_state=33)

#数据标准化
ss = StandardScaler()
X_train = ss.fit_transform(X_train)
X_test = ss.transform(X_test)

#预测
knc=KNeighborsClassifier()
knc.fit(X_train,y_train)    #训练
y_predict = knc.predict(X_test)     #预测

#评价
print('The Accuracy of K-Nearest Neighbor Classifier is:',knc.score(X_test,y_test))
print(classification_report(y_test,y_predict,target_names=iris.target_names))