VotingClassifier:不同的功能集 [英] VotingClassifier: Different Feature Sets
问题描述
我有两个不同的功能集(因此,行数相同且标签相同),在我的情况下是 DataFrames
:
I have two different feature sets (so, with same number of rows and the labels are the same), in my case DataFrames
:
df1
:
| A | B | C |
-------------
| 1 | 4 | 2 |
| 1 | 4 | 8 |
| 2 | 1 | 1 |
| 2 | 3 | 0 |
| 3 | 2 | 5 |
df2
:
| E | F |
---------
| 6 | 1 |
| 1 | 3 |
| 8 | 1 |
| 2 | 8 |
| 5 | 2 |
标签
:
| labels |
----------
| 5 |
| 5 |
| 1 |
| 7 |
| 3 |
我想用它们来训练 VotingClassifier
.但是拟合步骤仅允许指定一个功能集.目标是将 clf1
和 df1
匹配,将 clf2
和 df2
匹配.
I want to use them to train a VotingClassifier
. But the fitting step only allows to specify a single feature set. Goal is to fit clf1
with df1
and clf2
with df2
.
eclf = VotingClassifier(estimators=[('df1-clf', clf1), ('df2-clf', clf2)], voting='soft')
eclf.fit(...)
我应该如何处理这种情况?有什么简单的解决方案吗?
How should I proceed with this kind of situation? Is there any easy solution?
推荐答案
使自定义函数完成您想要实现的目标非常容易.
Its pretty easy to make custom functions to do what you want to achieve.
导入先决条件:
import numpy as np
from sklearn.preprocessing import LabelEncoder
def fit_multiple_estimators(classifiers, X_list, y, sample_weights = None):
# Convert the labels `y` using LabelEncoder, because the predict method is using index-based pointers
# which will be converted back to original data later.
le_ = LabelEncoder()
le_.fit(y)
transformed_y = le_.transform(y)
# Fit all estimators with their respective feature arrays
estimators_ = [clf.fit(X, y) if sample_weights is None else clf.fit(X, y, sample_weights) for clf, X in zip([clf for _, clf in classifiers], X_list)]
return estimators_, le_
def predict_from_multiple_estimator(estimators, label_encoder, X_list, weights = None):
# Predict 'soft' voting with probabilities
pred1 = np.asarray([clf.predict_proba(X) for clf, X in zip(estimators, X_list)])
pred2 = np.average(pred1, axis=0, weights=weights)
pred = np.argmax(pred2, axis=1)
# Convert integer predictions to original labels:
return label_encoder.inverse_transform(pred)
逻辑取自 VotingClassifier来源.
现在测试以上方法.首先获取一些数据:
Now test the above methods. First get some data:
from sklearn.datasets import load_iris
data = load_iris()
X = data.data
y = []
#Convert int classes to string labels
for x in data.target:
if x==0:
y.append('setosa')
elif x==1:
y.append('versicolor')
else:
y.append('virginica')
将数据拆分为训练并进行测试:
Split the data into train and test:
from sklearn.model_selection import train_test_split
X_train, X_test, y_train, y_test = train_test_split(X, y)
将X划分为不同的特征数据:
Divide the X into different feature datas:
X_train1, X_train2 = X_train[:,:2], X_train[:,2:]
X_test1, X_test2 = X_test[:,:2], X_test[:,2:]
X_train_list = [X_train1, X_train2]
X_test_list = [X_test1, X_test2]
获取分类列表:
from sklearn.neighbors import KNeighborsClassifier
from sklearn.svm import SVC
# Make sure the number of estimators here are equal to number of different feature datas
classifiers = [('knn', KNeighborsClassifier(3)),
('svc', SVC(kernel="linear", C=0.025, probability=True))]
将分类器与数据相匹配:
Fit the classifiers with the data:
fitted_estimators, label_encoder = fit_multiple_estimators(classifiers, X_train_list, y_train)
使用测试数据进行预测:
Predict using the test data:
y_pred = predict_from_multiple_estimator(fitted_estimators, label_encoder, X_test_list)
获取预测的准确性:
from sklearn.metrics import accuracy_score
print(accuracy_score(y_test, y_pred))
请随时询问是否有疑问.
Feel free to ask if any doubt.
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