简单的python决策树案例

机器学习入门——决策树的实例

写文章的目的是为了巩固所学，和方便回顾查找。如有讲错的地方，欢迎指出，谢谢。

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我们的数据集 tree(1).csv 长这样：

RID	age	income	student	credit_rating	buy
1	youth	high	no	fair	no
2	youth	high	no	excellent	no
3	middle_aged	high	no	fair	yes
4	senior	medium	no	fair	yes
5	senior	low	yes	fair	yes
6	senior	low	yes	excellent	no
7	middle_aged	low	yes	excellent	yes
8	youth	medium	no	fair	no
9	youth	low	yes	fair	yes
10	senior	medium	yes	fair	yes
11	youth	medium	yes	excellent	yes
12	middle_aged	medium	no	excellent	yes
13	middle_aged	high	yes	fair	yes
14	senior	medium	no	excellent	no

#导入必要的库
from sklearn.feature_extraction import DictVectorizer
import csv
from sklearn import preprocessing
from sklearn import tree

#加载数据文件
load_file = open(r'tree(1).csv')  
reader = csv.reade