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这篇文章主要介绍了python怎么实现随机森林的相关知识,内容详细易懂,操作简单快捷,具有一定借鉴价值,相信大家阅读完这篇python怎么实现随机森林文章都会有所收获,下面我们一起来看看吧。
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随机森林是一组决策树的商标术语。在随机森林中,我们收集了决策树(也称为“森林”)。为了基于属性对新对象进行分类,每棵树都有一个分类,我们称该树对该类“投票”。森林选择投票最多的类别(在森林中的所有树木上)。
每棵树的种植和生长如下:
如果训练集中的案例数为N,则随机抽取N个案例样本,但要进行替换。 该样本将成为树木生长的训练集。
如果有M个输入变量,则指定数字m << M,以便在每个节点上从M个中随机选择m个变量,并使用对这m个变量的最佳分割来分割节点。在森林生长期间,m的值保持恒定。
每棵树都尽可能地生长。没有修剪。
python代码实现:
'''
The following code is for the Random Forest
Created by - ANALYTICS VIDHYA
'''
# importing required libraries
import pandas as pd
from sklearn.ensemble import RandomForestClassifier
from sklearn.metrics import accuracy_score
# read the train and test dataset
train_data = pd.read_csv('train-data.csv')
test_data = pd.read_csv('test-data.csv')
# view the top 3 rows of the dataset
print(train_data.head(3))
# shape of the dataset
print('\nShape of training data :',train_data.shape)
print('\nShape of testing data :',test_data.shape)
# Now, we need to predict the missing
# target variable in the test data
# target variable - Survived
# seperate the independent and target variable on training data
train_x = train_data.drop(columns=['Survived'],axis=1)
train_y = train_data['Survived']
# seperate the independent and target variable on testing data
test_x = test_data.drop(columns=['Survived'],axis=1)
test_y = test_data['Survived']
'''
Create the object of the Random Forest model
You can also add other parameters and test your code here
Some parameters are : n_estimators and max_depth
Documentation of sklearn RandomForestClassifier:
https://scikit-learn.org/stable/modules/
generated/sklearn.ensemble.RandomForestClassifier.html
'''
model = RandomForestClassifier()
# fit the model with the training data
model.fit(train_x,train_y)
# number of trees used
print('Number of Trees used : ', model.n_estimators)
# predict the target on the train dataset
predict_train = model.predict(train_x)
print('\nTarget on train data',predict_train)
# Accuray Score on train dataset
accuracy_train = accuracy_score(train_y,predict_train)
print('\naccuracy_score on train dataset : ', accuracy_train)
# predict the target on the test dataset
predict_test = model.predict(test_x)
print('\nTarget on test data',predict_test)
# Accuracy Score on test dataset
accuracy_test = accuracy_score(test_y,predict_test)
print('\naccuracy_score on test dataset : ', accuracy_test)
运行结果:
Shape of training data : (712, 25)
Shape of testing data : (179, 25)
Number of Trees used : 10
Target on train data [0 1 1 0 0 0 0 0 0 0 0 1 1 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 1 1 0 0 1 0 0 0
1 0 0 0 1 0 1 0 1 1 0 1 0 1 0 0 0 0 0 0 0 1 0 1 1 1 0 0 1 0 01 0 0 0 0 0
0 1 1 0 0 1 0 0 1 1 1 0 0 0 1 0 1 0 0 1 0 0 0 1 1 0 0 1 0 1 11 0 1 0 0 0
0 0 0 1 1 0 0 1 0 1 0 1 1 0 0 0 1 0 0 1 0 0 0 1 0 1 0 1 0 0 00 1 0 1 1 0
0 0 0 1 1 0 0 1 0 0 0 0 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 00 0 1 0 0 1
0 1 1 1 1 0 0 1 0 1 0 0 1 1 1 1 0 0 0 1 1 1 1 0 0 0 0 1 1 0 00 1 0 0 0 0
0 0 0 0 1 0 0 0 1 0 1 0 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 1 1 1 01 0 0 0 1 0
0 1 1 0 1 1 1 0 1 1 0 0 1 0 0 1 1 1 1 0 0 1 0 0 0 1 1 0 0 1 10 0 0 0 0 0
0 0 1 1 0 1 1 0 1 0 1 1 1 0 0 0 1 0 1 1 0 0 0 0 1 0 1 0 0 0 00 0 0 0 0 1
1 0 0 1 1 0 1 0 0 0 1 0 1 0 0 0 1 0 1 0 0 1 0 1 0 0 0 1 0 1 00 0 0 0 1 0
0 0 0 0 0 0 1 0 0 1 0 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 1 1 1 1 01 1 0 1 1 1
0 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 0 1 1 0 0 1 0 1 0 1 1 11 0 0 1 0 0
0 1 0 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 0 0 0 0 0 0 1 1 10 0 0 0 0 0
0 0 1 1 1 0 0 1 0 1 1 0 1 0 0 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 00 0 0 1 0 1
1 0 0 0 0 1 0 0 0 1 0 1 0 1 1 1 0 0 0 0 0 0 1 1 1 0 0 1 1 1 01 0 1 0 0 1
0 0 0 1 1 0 0 1 0 0 1 0 1 0 0 1 0 0 1 1 0 0 1 1 0 1 0 0 0 0 11 0 1 1 1 0
1 0 1 0 1 1 0 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 0 0 1 0 1 0 0 0 00 0 0 0 0 1
0 0 0 1 0 1 1 1 1 0 1 1 0 0 1 0 1 0 0 1 0 0 1 1 1 1 0 1 0 0 01 0 1 1 1 0
1 0 0 0 1 0 0 1 0 0 1 0 1 0 0 1 1 0 0 1 0 0 0 0 0 0 1 0 0 0 00 0 1 0 1 0
1 0 1 1 1 0 0 1 0]
accuracy_score on train dataset : 0.973314606741573
Target on test data [0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 01 1 1 1 0 0 1 0 1 1 0 1 0 1 1 0
0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 0 1 1 0 0 1 1 1 0 0 0 00 1 0 0 0 0
1 0 0 0 0 0 0 0 0 1 0 0 1 1 0 1 0 0 1 0 1 0 0 0 1 0 0 0 0 0 11 0 1 1 0 1
0 1 0 0 0 1 1 1 1 1 0 1 1 0 1 1 0 0 1 1 0 0 1 1 0 0 0 1 0 1 00 0 0 0 0 0
0 0 0 1 1 0 0 0 0 1 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 0 0 0]
accuracy_score on test dataset : 0.8156424581005587
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