我的數據幀具有NaN值，但不應該

Question

我似乎無法訪問數據（非指數）的第一行，我有，所有其他人都很好：

df = pd.read_csv('stock_conf_GT_50.csv') 
df.head() 

數據看起來在這裏罰款：

 close  eqId  date IntDate expiry delta ivMid conf 
0 37.380005 7 2008-01-02 39447 1 50 0.3850 0.8663 
1 37.380005 7 2008-01-02 39447 1 90 0.5053 0.7876 
2 36.960007 7 2008-01-03 39448 1 50 0.3915 0.8597 
3 36.960007 7 2008-01-03 39448 1 90 0.5119 0.7438 
4 35.179993 7 2008-01-04 39449 1 50 0.4055 0.8454 

列名看起來太細：

df.columns 
Index([' close', 'eqId', 'date', 'IntDate', 'expiry', 'delta', 'ivMid', 
    'conf'], 
    dtype='object') 

我可以看到一些數據：

df['eqId'].head() 
0 7 
1 7 
2 7 
3 7 
4 7 
Name: eqId, dtype: int64 

但不是第一（非指數）柱：

df['close'].head() 

--------------------------------------------------------------------------- 
KeyError         Traceback (most recent call last) 
<ipython-input-118-f7ce330a88a7> in <module>() 
----> 1 df['close'].head() 

C:\Users\camcompco\AppData\Roaming\Python\Python34\site-  packages\pandas\core\frame.py in __getitem__(self, key) 
    1789    return self._getitem_multilevel(key) 
    1790   else: 
-> 1791    return self._getitem_column(key) 
    1792 
    1793  def _getitem_column(self, key): 

C:\Users\camcompco\AppData\Roaming\Python\Python34\site-packages\pandas\core\frame.py in _getitem_column(self, key) 
    1796   # get column 
    1797   if self.columns.is_unique: 
-> 1798    return self._get_item_cache(key) 
    1799 
    1800   # duplicate columns & possible reduce dimensionaility 

    C:\Users\camcompco\AppData\Roaming\Python\Python34\site-packages\pandas\core\generic.py in _get_item_cache(self, item) 
    1082   res = cache.get(item) 
    1083   if res is None: 
-> 1084    values = self._data.get(item) 
    1085    res = self._box_item_values(item, values) 
    1086    cache[item] = res 

C:\Users\camcompco\AppData\Roaming\Python\Python34\site-packages\pandas\core\internals.py in get(self, item, fastpath) 
    2849 
    2850    if not isnull(item): 
-> 2851     loc = self.items.get_loc(item) 
    2852    else: 
    2853     indexer = np.arange(len(self.items)) [isnull(self.items)] 

C:\Users\camcompco\AppData\Roaming\Python\Python34\site-packages\pandas\core\index.py in get_loc(self, key, method) 
    1576   """ 
    1577   if method is None: 
-> 1578    return self._engine.get_loc(_values_from_object(key)) 
    1579 
    1580   indexer = self.get_indexer([key], method=method) 

pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:3811)() 

pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:3691)() 

pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12336)() 

pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12287)() 

KeyError: 'close' 

這裏是我所得到的，當我運行這段代碼：

DataFrame(df,columns=['close','ivMid','eqId'],index=None) 

    close ivMid eqId 
    0 NaN 0.3850 7 
    1 NaN 0.5053 7 
    2 NaN 0.3915 7 
    3 NaN 0.5119 7 
    4 NaN 0.4055 7 
    5 NaN 0.5183 7 
    6 NaN 0.4464 7 
    7 NaN 0.5230 7 
    8 NaN 0.4453 7 
    9 NaN 0.4826 7 
    10 NaN 0.5668 7 

Answer 1

你可以看到，近有前一個空格它在指數：

Index([' close', 'eqId', 'date', 'IntDate', 'expiry', 'delta', 'ivMid', 

因此KeyError當試圖訪問'close'專欄。
您必須通過df[' close']訪問它。

另一種方法是應用帶向列以確保他們沒有前導空格：

df.index = df.index.map(lambda x: x.strip())