pipeline for RandomOversampler, RandomForestClassifier & GridSearchCV

Question

I am working on a binary text classification problem. As the classes are highly imbalanced, I am using sampling techniques like RandomOversampler(). Then for classification I would use RandomForestClassifier() whose parameters need to be tuned using GridSearchCV().

I am trying to create a pipeline to do these in order but failed so far. It throws invalid parameters.

param_grid = {
             'n_estimators': [5, 10, 15, 20],
             'max_depth': [2, 5, 7, 9]
         }
grid_pipe = make_pipeline(RandomOverSampler(),RandomForestClassifier())
grid_searcher = GridSearchCV(grid_pipe,param_grid,cv=10)
grid_searcher.fit(tfidf_train[predictors],tfidf_train[target])

Asked By: Sreenath1986

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Source

Answer 1

The parameters you defined in the params is for RandomForestClassifier, but in the gridSearchCV, you are not passing a RandomForestClassifier object.

You are passing a pipeline object, for which you have to rename the parameters to access the internal RandomForestClassifier object.

Change them to:

param_grid = {
             'randomforestclassifier__n_estimators': [5, 10, 15, 20],
             'randomforestclassifier__max_depth': [2, 5, 7, 9]
             }

And it will work.

Answered By: Vivek Kumar

Answer 2

Thanks for A2A. Ideally the parameters are defined as follows:

Create a pipeline for the transformers to be applied on the data

pipeline = make_pipeline([('variable initialization 1',transformers1()),('variable initialization 2',transformers2()),]

Note: Do not forget to end the pipeline with a ‘,’ before closing off square brackets

eg:pipeline = make_pipeline([('random_over_sampler',RandomOverSampler()),('RandomForestClassifier', RandomForestClassifier()),]

Create a parameter grid

param_grid = {'transformations/algorithm'__'parameter_in_transformations/algorithm':[parameters]}

eg: param_grid = {RandomOverSampler__sampling_strategy:['auto']}

Answered By: Giri19

pipeline for RandomOversampler, RandomForestClassifier & GridSearchCV

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