How can you perform a hyperparameter grid search with Orange?

Question

Is there a way to perform a hyperparameter grid search with Orange?

Answer 1

Yes, you can perform a hyperparameter grid search with Orange by using the GridSearchCV class from the sklearn.model_selection module, as Orange itself doesn't provide a built-in method for hyperparameter grid search. Since Orange is built on top of scikit-learn, it is compatible with scikit-learn's tools and models.

import Orange
from sklearn.datasets import load_iris
from sklearn.model_selection import GridSearchCV
from sklearn.tree import DecisionTreeClassifier
from sklearn.pipeline import Pipeline
from sklearn import preprocessing


#load the data and convert it into an Orange table
iris = load_iris()
iris_data = Orange.data.Table(iris.data, iris.target)

#Create a scikit-learn pipeline with the desired preprocessor and estimator
pipeline = Pipeline([
    ('scaler', preprocessing.StandardScaler()),  # Preprocessing (optional)
    ('classifier', DecisionTreeClassifier())  # Your classifier (e.g., Decision Tree)
])


#define the hyperparameter search grid
param_grid = {
    'scaler': [preprocessing.StandardScaler(), preprocessing.MinMaxScaler()],
    'classifier__criterion': ['gini', 'entropy'],
    'classifier__max_depth': [3, 4, 5, 6]
}

#create the GridSearchCV object and fit it into data
grid_search = GridSearchCV(pipeline, param_grid, scoring='accuracy', cv=5)
grid_search.fit(iris_data.X, iris_data.Y)

#print the best hyperparameters and corresponding scores
print("Best hyperparameters:", grid_search.best_params_)
print("Best score:", grid_search.best_score_)

Best hyperparameters: {'classifier__criterion': 'gini', 'classifier__max_depth': 4, 'scaler': MinMaxScaler()}
Best score: 0.9666666666666668