Aprenda Voting: Hard and Soft | Stacking and Voting Ensembles

Voting ensembles combine predictions from multiple base models to make a final decision. There are two main types: hard voting and soft voting.

Hard voting takes the majority class label predicted by the base models;
Soft voting averages the predicted probabilities and selects the class with the highest average probability.

Hard voting is typically used when base models output class labels, while soft voting is used when base models can output class probabilities. Soft voting can leverage the confidence of each model's prediction.

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Comparing ensemble methods: voting combines predictions in parallel, bagging averages predictions from models trained on different data samples, and boosting combines models sequentially to correct errors.


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from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler
from sklearn.linear_model import LogisticRegression
from sklearn.tree import DecisionTreeClassifier
from sklearn.svm import SVC
from sklearn.ensemble import VotingClassifier
from sklearn.metrics import accuracy_score

# Load dataset
iris = load_iris()
X, y = iris.data, iris.target

# Split data
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=42, stratify=y)

# Standardize features for SVC and Logistic Regression
scaler = StandardScaler()
X_train_scaled = scaler.fit_transform(X_train)
X_test_scaled = scaler.transform(X_test)

# Define base models
clf1 = LogisticRegression(random_state=42, max_iter=200)
clf2 = DecisionTreeClassifier(random_state=42)
clf3 = SVC(probability=True, random_state=42)

# Hard voting ensemble (majority vote)
hard_voting = VotingClassifier(
    estimators=[('lr', clf1), ('dt', clf2), ('svc', clf3)],
    voting='hard'
)
hard_voting.fit(X_train_scaled, y_train)
y_pred_hard = hard_voting.predict(X_test_scaled)
print("Hard Voting Accuracy:", accuracy_score(y_test, y_pred_hard))

# Soft voting ensemble (average probabilities)
soft_voting = VotingClassifier(
    estimators=[('lr', clf1), ('dt', clf2), ('svc', clf3)],
    voting='soft'
)
soft_voting.fit(X_train_scaled, y_train)
y_pred_soft = soft_voting.predict(X_test_scaled)
print("Soft Voting Accuracy:", accuracy_score(y_test, y_pred_soft))

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Seção 4. Capítulo 1

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Voting ensembles combine predictions from multiple base models to make a final decision. There are two main types: hard voting and soft voting.

Hard voting takes the majority class label predicted by the base models;
Soft voting averages the predicted probabilities and selects the class with the highest average probability.

Study More


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from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler
from sklearn.linear_model import LogisticRegression
from sklearn.tree import DecisionTreeClassifier
from sklearn.svm import SVC
from sklearn.ensemble import VotingClassifier
from sklearn.metrics import accuracy_score

# Load dataset
iris = load_iris()
X, y = iris.data, iris.target

# Split data
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=42, stratify=y)

# Standardize features for SVC and Logistic Regression
scaler = StandardScaler()
X_train_scaled = scaler.fit_transform(X_train)
X_test_scaled = scaler.transform(X_test)

# Define base models
clf1 = LogisticRegression(random_state=42, max_iter=200)
clf2 = DecisionTreeClassifier(random_state=42)
clf3 = SVC(probability=True, random_state=42)

# Hard voting ensemble (majority vote)
hard_voting = VotingClassifier(
    estimators=[('lr', clf1), ('dt', clf2), ('svc', clf3)],
    voting='hard'
)
hard_voting.fit(X_train_scaled, y_train)
y_pred_hard = hard_voting.predict(X_test_scaled)
print("Hard Voting Accuracy:", accuracy_score(y_test, y_pred_hard))

# Soft voting ensemble (average probabilities)
soft_voting = VotingClassifier(
    estimators=[('lr', clf1), ('dt', clf2), ('svc', clf3)],
    voting='soft'
)
soft_voting.fit(X_train_scaled, y_train)
y_pred_soft = soft_voting.predict(X_test_scaled)
print("Soft Voting Accuracy:", accuracy_score(y_test, y_pred_soft))

Tudo estava claro?

Obrigado pelo seu feedback!

Seção 4. Capítulo 1