Scikit-learn using GridSearchCV on DecisionTreeClassifier

Question

I tried to use GridSearchCV on DecisionTreeClassifier, but get the following error: TypeError: unbound method get_params() must be called with DecisionTreeClassifier instance as first argument (got nothing instead)

here's my code:

from sklearn.tree import DecisionTreeClassifier, export_graphviz
from sklearn.model_selection import GridSearchCV
from sklearn.cross_validation import  cross_val_score

X, Y = createDataSet(filename)
tree_para = {'criterion':['gini','entropy'],'max_depth':[4,5,6,7,8,9,10,11,12,15,20,30,40,50,70,90,120,150]}
clf = GridSearchCV(DecisionTreeClassifier, tree_para, cv=5)
clf.fit(X, Y)

Answer 1

In your call to GridSearchCV method, the first argument should be an instantiated object of the DecisionTreeClassifier instead of the name of the class. It should be

clf = GridSearchCV(DecisionTreeClassifier(), tree_para, cv=5)

Check out the example here for more details.

Hope that helps!