决策树模型C50错误

Question

#Divide data into train and test
X = Train_data.values[:, 0:15]
Y = Train_data.values[:,15]

X_train, X_test, y_train, y_test = train_test_split( X, Y, test_size = 0.2)
#Decision Tree
C50_model = tree.DecisionTreeClassifier(criterion='entropy').fit(X_train, y_train)

对于此代码，我收到一条错误消息，

ValueError: could not convert string to float: ' no'

任何人都可以帮忙，或者为决策树提供更好的代码吗？