import numpy as np
from sklearn.datasets import load_iris
from sklearn import tree

iris = load_iris()
test_idx = [0, 50, 100]

#training data
train_target = np.delete( iris.target, test_idx )
train_data = np.delete( iris.data, test_idx, axis=0 )

#testing data
test_target = iris.target[ test_idx ]
test_data = iris.data[test_idx]

clf = tree.DecisionTreeClassifier()
clf.fit( train_data, train_target )

print test_target
print clf.predict( test_data )
