TypeError：slice索引必须是整数或None或者具有__index__方法env：python3.6

Question

代码如下。

from sklearn import svm,datasets    
class Dataset:
    def __init__(self, name):
        self.name = name    
    def download_data(self):
        if self.name == 'iris':
            self.download_data = datasets.load_iris()
        elif self.name == 'digits':
            self.download_data = datasets.load_digits()
        else:
            print("Dataset Error:No name datasets.")

    def generate_xy(self):
        self.download_data()
        x = self.download_data.data
        y = self.download_data.target
        print('\nOriginal data looks like this:\n',x)
        print('\nLabels looks like this:\n',y)
        print('\n x:', len(x),' ',len(x[0]))
        print('\n y:', len(y))
        return x,y

    def get_train_test_set(self, ratio):
        x, y = self.generate_xy()
        n_samples = len(x)
        n_train = n_samples * ratio

        X_train = x[:n_train]
        Y_train = y[:n_train]
        X_test = x[n_train:]
        Y_test = y[n_train:]

       return X_train, Y_train, X_test, Y_test


data = Dataset('digits')
X_train, Y_train, X_test, Y_test = data.get_train_test_set(0.8)
clf = svm.SVC()
print(clf.fit(X_train, Y_train))
test_point = X_test[12]
y_true = Y_test[12]
print(clf.predict(test_point))
print(y_true)

predict_result = []
for element in X_test:
    predict_result.append(clf.predict(element))
print('predict_result.len:', len(predict_result))
print('Y_test.len', len(Y_test))

if len(predict_result) != len(Y_test):
    print('something wrong with the caculation, predict_result.len:',len(predict_result), 'Y_test.len:%d',len(Y_test))
else:
    cnt = 0
    for i in range(0, len(predict_result), 1):
        if(predict_result[i] == Y_test[i]):
            cnt += 1


precision_ratio = cnt / len(predict_result)
print('precision ratio = ', precision_ratio)

编译器指出这两个地方： X_train，Y_train，X_test，Y_test = data.get_train_test_set（0.8） X_train = x [：n_train]

我想也许是因为＆＃39; n_train＆＃39;浮动，这是不正确的。所以我纠正了这样的代码：

X_train = x[:int(n_train)]

它仍然是错的。我不知道我错在哪里。