使用 python 创建决策树

Question

我正在使用名为 "wine" 的数据集创建决策树：我正在尝试执行以下代码：

dt = c.fit(X_train, y_train)

创建决策树的图像：

其中 "Malik Shahid Ali" 是图像的 location/path

def show_tree(tree, features, path):
    f = io.StringIO()
    export_graphviz(tree, out_file=f, feature_names=features)
    pydotplus.graph_from_dot_data(f.getvalue()).write_png("Malik Shahid Ali")
    img = misc.imread("Malik Shahid Ali")
    plt.imshow(img)

调用图像：

show_tree(dt, features, 'dec_tree_01.png')

但是当我调用图像时出现以下错误:

GraphViz's executables not found

导入部分：

import numpy as np
import pandas as pd
from sklearn import tree
from sklearn.tree import DecisionTreeClassifier, export_graphviz
from sklearn.model_selection import train_test_split
import graphviz
import pydotplus
import io
from scipy import misc
import matplotlib.pyplot as plt #sets up plotting under plt
import seaborn as sb
from pylab import rcParams

正在读取 csv 数据集

data=pd.read_csv('C:/Users/malik/Desktop/wine.csv',low_memory=False)
data.head()

train, test = train_test_split(data,test_size=0.15)

print("Training size: {} Test size: {}".format(len(train),len(test)))

c=DecisionTreeClassifier(min_samples_split=2)

features = ["id","Alcohol","Malic acid","Ash","Alcalinity of ash","Magnesium","Total phenols","Flavanoids","Field9Nonflavanoid phenols","Proanthocyanins","Color intensity","Hue","OD280/OD315 of diluted wines","Proline"]

X_train = train[features]
y_train = train["id"]

X_test = test[features]
y_test = test["id"]

y_test

dt = c.fit(X_train, y_train)

可执行文件的路径：

import os     
os.environ["PATH"] += os.pathsep + 'E:\Graphviz2.38\bin'

图像函数：

def show_tree(tree, features, path):
    f = io.StringIO()
    export_graphviz(tree, out_file=f, feature_names=features)
    pydotplus.graph_from_dot_data(f.getvalue()).write_png(path)
    img = misc.imread(path)

    plt.imshow(img)

show_tree(dt, features, 'dec_tree_01.png')

现在在这个命令上 jupyter 给出了这样的错误：

E:\python\lib\site-packages\pydotplus\graphviz.py in create(self, prog, format)
   1958             if self.progs is None:
   1959                 raise InvocationException(
-> 1960                     'GraphViz\'s executables not found')
   1961 
   1962         if prog not in self.progs:

InvocationException: GraphViz's executables not found

Answer 1

我是 re-purposing 我对相关问题的回答 here。

确保您已经安装了实际的可执行文件，而不仅仅是 python 包。我使用了 conda 的安装包 here（推荐超过 pip install graphviz，因为 pip 安装没有包括实际的 GraphViz executables).

更新

在一天结束时，向环境变量 PATH 添加了必要文件目录的格式不正确的字符串路径。请务必在目录的字符串路径中添加双反斜杠，例如：

import os
os.environ["PATH"] += os.pathsep + 'E:\Graphviz2.38\bin\'

使用 python 创建决策树

Creating Decision Tree using python

python

graphviz

pandas

jupyter

更新