I want to use scikit-learn's GridSearchCV to optimise a BaggingClassifier that uses a support vector classifier (SVC). I want the grid search to search over parameters for both the BaggingClassifier and the SVC.

I have tried this setup:

svc_pipe = Pipeline([
     ('svc', SVC(probability=True)),
pipe = Pipeline([
     ('bag', BaggingClassifier(svc_pipe, no_estimators=50)),

params = {
    'bag__bootstrap_features' : [True, False],
    'bag__svc__kernel': ['linear', 'rbf'],
    'bag__svc__decision_function_shape': ['ovo', 'ovr']

rnd_search = GridSearchCV(pipe, param_grid=params)

but I get this error:

ValueError: Invalid parameter svc for estimator BaggingClassifier(base_estimator=Pipeline(memory=None,
     steps=[('svc', SVC(C=1.0, cache_size=200, class_weight=None, coef0=0.0,
  decision_function_shape='ovr', degree=3, gamma='auto', kernel='rbf',
  max_iter=-1, probability=True, shrinking=True,
  tol=0.001, verbose=False))]),
         bootstrap=True, bootstrap_features=True, max_features=1.0,
         max_samples=1.0, n_estimators=50, n_jobs=-1, oob_score=False,
         verbose=0, warm_start=False). Check the list of available parameters with `estimator.get_params().keys()`.

Can someone show me what I have done wrong?


There is a typo in pipe, no_estimators should be n_estimators.

To address your problem, if you run the following piece of code:

for param in rnd_search.get_params().keys():

This will show you how the parameters are passed to different parts of the pipeline, the parameters of interest are:

  • bag__base_estimator__svc__kernel
  • bag__base_estimator__svc__decision_function_shape

So you were almost there, you were just missing base_estimator__ in the svc pipeline parameters. All you need to do is change the svc parameters like so:

params = {
    'bag__bootstrap_features' : [True, False],
    'bag__base_estimator__svc__kernel': ['linear', 'rbf'],
    'bag__base_estimator__svc__decision_function_shape': ['ovo', 'ovr']

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.