Python 在不更改我的代码的情况下，恢复错误似乎是随机的。可能的内存错误？

我正在阅读一本sklearn教程，其中有以下部分：

Next, we create a TfidfVectorizer. Recall from Chapter 3, Feature Extraction and Preprocessing, that TfidfVectorizer combines CountVectorizer and TfidfTransformer. We fit it with the training messages, and transform both the training and test messages:

>>> vectorizer = TfidfVectorizer()
>>> X_train = vectorizer.fit_transform(X_train_raw)
>>> X_test = vectorizer.transform(X_test_raw)
Finally, we create an instance of LogisticRegression and train our model. Like LinearRegression, LogisticRegression implements the fit() and predict() methods. As a sanity check, we printed a few predictions for manual inspection:

>>> classifier = LogisticRegression()
>>> classifier.fit(X_train, y_train)
>>> predictions = classifier.predict(X_test)
>>> for i, prediction in enumerate(predictions[:5]):
>>>     print 'Prediction: %s. Message: %s' % (prediction, X_test_raw[i])
The following is the output of the script:

Prediction: ham. Message: If you don't respond imma assume you're still asleep and imma start calling n shit
Prediction: spam. Message: HOT LIVE FANTASIES call now 08707500020 Just 20p per min NTT Ltd, PO Box 1327 Croydon CR9 5WB 0870 is a national rate call
Prediction: ham. Message: Yup... I havent been there before... You want to go for the yoga? I can call up to book 
Prediction: ham. Message: Hi, can i please get a  <#>  dollar loan from you. I.ll pay you back by mid february. Pls.
Prediction: ham. Message: Where do you need to go to get it?

我接着说：

ddir = (sys.argv[1])


df = pd.read_csv(ddir + '/SMSSpamCollection', delimiter='\t', header=None)

#print df.head
#print 'Number of spam messages: ', df[df[0] == 'spam'][0].count()
#print 'Number of ham messages: ', df[df[0] == 'ham'][0].count()

X_train_raw, X_test_raw, y_train, y_test = train_test_split(df[1], df[0])

vectorizer = TfidfVectorizer()

X_train = vectorizer.fit_transform(X_train_raw)
X_test = vectorizer.transform(X_test_raw)


classifier = LogisticRegression()
classifier.fit(X_train, y_train)
predictions = classifier.predict(X_test)

for i, pdn in enumerate(predictions):
    print 'Prediction: %s. Message: %s' % (pdn, X_test_raw[i])

然而，由于某种原因，这给了我一个错误。认为这是我的修改，我重写了我的代码，按照书中的一行接一行：

for i, prediction in enumerate(predictions[:5]):
    print 'Prediction: %s. Message: %s' % (prediction, X_test_raw[i])

然而，在崩溃之前，这只打印了两个答案：

Number of spam messages: 747
Number of ham messages: 4825
['ham' 'ham' 'ham' ..., 'ham' 'ham' 'ham']
Prediction: ham. Message: Go until jurong point, crazy.. Available only in bugis n great world la e buffet... Cine there got amore wat...
Prediction: ham. Message: Ok lar... Joking wif u oni...
Traceback (most recent call last):
  File "Chapter4[B-FLGTLG][Y-SF]--[DC].py", line 38, in <module>
    print 'Prediction: %s. Message: %s' % (prediction, X_test_raw[i])
  File "/usr/local/lib/python2.7/dist-packages/pandas/core/series.py", line 583, in __getitem__
    result = self.index.get_value(self, key)
  File "/usr/local/lib/python2.7/dist-packages/pandas/indexes/base.py", line 1980, in get_value
    tz=getattr(series.dtype, 'tz', None))
  File "pandas/index.pyx", line 103, in pandas.index.IndexEngine.get_value (pandas/index.c:3332)
  File "pandas/index.pyx", line 111, in pandas.index.IndexEngine.get_value (pandas/index.c:3035)
  File "pandas/index.pyx", line 159, in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)
  File "pandas/hashtable.pyx", line 303, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:6610)
  File "pandas/hashtable.pyx", line 309, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:6554)
KeyError: 2

垃圾邮件数量：747
ham消息数：4825
[“火腿”“火腿”“火腿”…，“火腿”“火腿”“火腿”]
预测：火腿。留言：一直走到句容点，疯了。。仅在bugis n great world la e自助餐厅提供。。。电影里有阿莫尔·沃特。。。
预测：火腿。信息：好的，我。。。和你开玩笑。。。
回溯（最近一次呼叫最后一次）：
文件“第4章[B-FLGTLG][Y-SF]-[DC].py”，第38行，中
打印的预测：%s。消息：%s'（预测，X\u测试\u原始[i]）
文件“/usr/local/lib/python2.7/dist packages/pandas/core/series.py”，第583行，在__
结果=self.index.get_值（self，key）
文件“/usr/local/lib/python2.7/dist packages/pandas/index/base.py”，第1980行，在get_值中
tz=getattr（series.dtype，'tz'，无））
pandas.index.IndexEngine.get_值（pandas/index.c:3332）中第103行的文件“pandas/index.pyx”
pandas.index.IndexEngine.get_值（pandas/index.c:3035）中第111行的文件“pandas/index.pyx”
pandas.index.IndexEngine.get_loc（pandas/index.c:4018）中的文件“pandas/index.pyx”，第159行
pandas.hashtable.Int64HashTable.get_项（pandas/hashtable.c:6610）中第303行的文件“pandas/hashtable.pyx”
pandas.hashtable.Int64HashTable.get_项（pandas/hashtable.c:6554）中第309行的文件“pandas/hashtable.pyx”
关键错误：2

现在问题来了：我第二次运行了完全相同的脚本，没有更改任何一行，它给了我一个不同的错误：

垃圾邮件数量：747
ham消息数：4825
[“火腿”“火腿”“火腿”…，“火腿”“火腿”“火腿”]
回溯（最近一次呼叫最后一次）：
文件“第4章[B-FLGTLG][Y-SF]-[DC].py”，第38行，中
打印的预测：%s。消息：%s'（预测，X\u测试\u原始[i]）
文件“/usr/local/lib/python2.7/dist packages/pandas/core/series.py”，第583行，在__
结果=self.index.get_值（self，key）
文件“/usr/local/lib/python2.7/dist packages/pandas/index/base.py”，第1980行，在get_值中
tz=getattr（series.dtype，'tz'，无））
pandas.index.IndexEngine.get_值（pandas/index.c:3332）中第103行的文件“pandas/index.pyx”
pandas.index.IndexEngine.get_值（pandas/index.c:3035）中第111行的文件“pandas/index.pyx”
pandas.index.IndexEngine.get_loc（pandas/index.c:4018）中的文件“pandas/index.pyx”，第159行
pandas.hashtable.Int64HashTable.get_项（pandas/hashtable.c:6610）中第303行的文件“pandas/hashtable.pyx”
pandas.hashtable.Int64HashTable.get_项（pandas/hashtable.c:6554）中第309行的文件“pandas/hashtable.pyx”
关键错误：0

这怎么可能呢？我是否有一些低级的ram bug在破坏python本身？数据在这里：以防有人想跟进。

更新

我从这里找到了一个解决方案：

我改变了：

print 'Prediction: %s. Message: %s' % (pdn, X_test_raw[i])

到

现在它运行良好：

Number of spam messages: 747
Number of ham messages: 4825
['ham' 'spam' 'ham' ..., 'spam' 'ham' 'ham']
Prediction: ham. Message: Well done, blimey, exercise, yeah, i kinda remember wot that is, hmm. 
Prediction: spam. Message: U have won a nokia 6230 plus a free digital camera. This is what u get when u win our FREE auction. To take part send NOKIA to 83383 now. POBOX114/14TCR/W1 16
Prediction: ham. Message: I doubt you could handle 5 times per night in any case...
Prediction: ham. Message: I've told you everything will stop. Just dont let her get dehydrated.
Prediction: ham. Message: AH POOR BABY!HOPE URFEELING BETTERSN LUV! PROBTHAT OVERDOSE OF WORK HEY GO CAREFUL SPK 2 U SN LOTS OF LOVEJEN XXX.

更新

我从这里找到了一个解决方案：

我改变了：

print 'Prediction: %s. Message: %s' % (pdn, X_test_raw[i])

到

现在它运行良好：

Number of spam messages: 747
Number of ham messages: 4825
['ham' 'spam' 'ham' ..., 'spam' 'ham' 'ham']
Prediction: ham. Message: Well done, blimey, exercise, yeah, i kinda remember wot that is, hmm. 
Prediction: spam. Message: U have won a nokia 6230 plus a free digital camera. This is what u get when u win our FREE auction. To take part send NOKIA to 83383 now. POBOX114/14TCR/W1 16
Prediction: ham. Message: I doubt you could handle 5 times per night in any case...
Prediction: ham. Message: I've told you everything will stop. Just dont let her get dehydrated.
Prediction: ham. Message: AH POOR BABY!HOPE URFEELING BETTERSN LUV! PROBTHAT OVERDOSE OF WORK HEY GO CAREFUL SPK 2 U SN LOTS OF LOVEJEN XXX.