Pandas read_csv 无法正确加载逗号分隔的 CSV
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Pandas read_csv does not load a comma separated CSV properly
提问by user8385498
Now,I analyze Titanic challenge of Kaggel.
My code is this:
现在，我分析了 Kaggel 的泰坦尼克号挑战。我的代码是这样的：
But my ideal output is:
但我的理想输出是：
So,in my last code is
所以，在我的最后一个代码是
df["Age"].fillna(df.Age.median(), inplace=True)
and error happens
和错误发生
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/indexes/base.py in get_loc(self, key, method, tolerance)
2133 try:
-> 2134 return self._engine.get_loc(key)
2135 except KeyError:
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4433)()
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4279)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13742)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13696)()
KeyError: 'Age'
During handling of the above exception, another exception occurred:
KeyError Traceback (most recent call last)
<ipython-input-4-9763f0a9951c> in <module>()
----> 1 df["Age"].fillna(df.Age.median(), inplace=True)
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/core/frame.py in __getitem__(self, key)
2057 return self._getitem_multilevel(key)
2058 else:
-> 2059 return self._getitem_column(key)
2060
2061 def _getitem_column(self, key):
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/core/frame.py in _getitem_column(self, key)
2064 # get column
2065 if self.columns.is_unique:
-> 2066 return self._get_item_cache(key)
2067
2068 # duplicate columns & possible reduce dimensionality
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/core/generic.py in _get_item_cache(self, item)
1384 res = cache.get(item)
1385 if res is None:
-> 1386 values = self._data.get(item)
1387 res = self._box_item_values(item, values)
1388 cache[item] = res
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/core/internals.py in get(self, item, fastpath)
3541
3542 if not isnull(item):
-> 3543 loc = self.items.get_loc(item)
3544 else:
3545 indexer = np.arange(len(self.items))[isnull(self.items)]
/Users/XXXi/anaconda/envs/py36/lib/python3.6/site-packages/pandas/indexes/base.py in get_loc(self, key, method, tolerance)
2134 return self._engine.get_loc(key)
2135 except KeyError:
-> 2136 return self._engine.get_loc(self._maybe_cast_indexer(key))
2137
2138 indexer = self.get_indexer([key], method=method, tolerance=tolerance)
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4433)()
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4279)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13742)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13696)()
KeyError: 'Age'
I use sep=','so I really cannot understand why this code cannot separate in each comma.How can I fix this?
我使用sep=','所以我真的不明白为什么这段代码不能在每个逗号中分开。我该如何解决这个问题？
I followed one answer,but error happens (I do not know why)
我遵循了一个答案，但发生错误（我不知道为什么）
My data is 
我的数据是
采纳答案by cs95
Attention!
注意力！
The main issue was downloading the data. If you run a problem of loading and processing the Kaggle Titanic Dataset, you may re-download the CSV from hereand re-run your program.
主要问题是下载数据。如果您在加载和处理 Kaggle Titanic 数据集时遇到问题，您可以从这里重新下载 CSV并重新运行您的程序。
You can pass delimiter=',':
你可以通过delimiter=','：
df = pd.read_csv("Desktop/data/train.csv", delimiter=',')
print(df.head())
PassengerId Survived Pclass \
0 1 0 3
1 2 1 1
2 3 1 3
3 4 1 1
4 5 0 3
Name Sex Age SibSp \
0 Braund, Mr. Owen Harris male 22.0 1
1 Cumings, Mrs. John Bradley (Florence Briggs Th... female 38.0 1
2 Heikkinen, Miss. Laina female 26.0 0
3 Futrelle, Mrs. Jacques Heath (Lily May Peel) female 35.0 1
4 Allen, Mr. William Henry male 35.0 0
Parch Ticket Fare Cabin Embarked
0 0 A/5 21171 7.2500 NaN S
1 0 PC 17599 71.2833 C85 C
2 0 STON/O2. 3101282 7.9250 NaN S
3 0 113803 53.1000 C123 S
4 0 373450 8.0500 NaN S
print(df.columns)
Index(['PassengerId', 'Survived', 'Pclass', 'Name', 'Sex', 'Age', 'SibSp',
'Parch', 'Ticket', 'Fare', 'Cabin', 'Embarked'],
dtype='object')
Next, you can create a mapping of sorts:
接下来，您可以创建各种映射：
mapping = {'male' : 0, 'female' : 1}
And you'll call pd.Series.replace:
你会打电话给pd.Series.replace：
df.Sex = df.Sex.replace(mapping)
print(df.Sex)
0 0
1 1
2 1
3 1
4 0
Name: Sex, dtype: int64
回答by StefanK
Your read_csv looks fine, the replace in the same line seems to be causing trouble.
您的 read_csv 看起来不错，同一行中的替换似乎引起了麻烦。
Try to first read the csv as is into the variable df. This way your code will be cleaner.
尝试首先将 csv 原样读取到变量 df 中。这样你的代码会更干净。
df = pd.read_csv('Desktop/data/train.csv',sep=',')
df['Sex'] = df['Sex'].map( {'female': 1, 'male': 0} )
But you can leave the sep argument altogether as comma is standard delimiter
但是您可以完全保留 sep 参数，因为逗号是标准分隔符
Alternatively do the cleaning with replace on a new line after you read the file into df and use
inplace=True:
或者，在将文件读入 df 并使用后，在新行上使用替换进行清理
inplace=True：
df['Sex'].replace({'male': 0, 'female': 1}, inplace=True)
General advice:
一般建议：
Kaggle webpage supports script sharing and commenting in kernel section. Try to look at it to see how you can go about the analysis if you are stuck somewhere:
Kaggle 网页支持内核部分的脚本共享和评论。试着看看它，看看如果你被困在某个地方，你可以如何进行分析：
