use random forest to classifier review, but hat key error? - python-2.7

Question

I have follow code in python:
from sklearn.ensemble import RandomForestClassifier
forest = RandomForestClassifier(n_estimators = 100)
forest = forest.fit( train_data_features, train["sentiment"] )
but have key error for "sentiment", I don't know why,
train = pd.read_csv("labeledTrainData.tsv", header=0, delimiter="\t", quoting=3)
-Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site--packages/pandas/core/frame.py", line 1780, in __getitem__
return self._getitem_column(key)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/frame.py", line 1787, in _getitem_column
return self._get_item_cache(key)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/generic.py", line 1068, in _get_item_cache
values = self._data.get(item)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/internals.py", line 2849, in get
loc = self.items.get_loc(item)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/index.py", line 1402, in get_loc
return self._engine.get_loc(_values_from_object(key))
File "pandas/index.pyx", line 134, in pandas.index.IndexEngine.get_loc (pandas/index.c:3807)
File "pandas/index.pyx", line 154, in pandas.index.IndexEngine.get_loc (pandas/index.c:3687)
File "pandas/hashtable.pyx", line 696, in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12310)
File "pandas/hashtable.pyx", line 704, in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12261)
KeyError: 'sentiment'

Answer 1

Are you doing the Kaggle competition? https://www.kaggle.com/c/word2vec-nlp-tutorial/data
Are you sure you have downloaded and decompressed the file ok? The first part of the file reads:
id sentiment review
"5814_8" 1 "With all this stuff go
This works for me:
>>> train = pd.read_csv("labeledTrainData.tsv", delimiter="\t")
>>> train.columns
Index([u'id', u'sentiment', u'review'], dtype='object')
>>> train.head(3)
id sentiment review
0 5814_8 1 With all this stuff going down at the moment w...
1 2381_9 1 \The Classic War of the Worlds\" by Timothy Hi...
2 7759_3 0 The film starts with a manager (Nicholas Bell)...
You should check the columns are setup correctly in the train variable. You should have a sentiment column. That column seems to be missing in your dataframe.