python Pandas : filter out records with null or empty string for a given field

Question

我正在尝试过滤掉数据框中 field_A 为 null 或空字符串的记录，如下所示:

my_df[my_df.editions is not None]
my_df.shape

这给我错误:

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-40-e1969e0af259> in <module>()
      1 my_df['editions'] = my['editions'].astype(str)
----> 2 my_df = my_df[my_df.editions is not None]
      3 my_df.shape

/home/edamame/anaconda2/lib/python2.7/site-packages/pandas/core/frame.pyc in __getitem__(self, key)
   1995             return self._getitem_multilevel(key)
   1996         else:
-> 1997             return self._getitem_column(key)
   1998 
   1999     def _getitem_column(self, key):

/home/edamame/anaconda2/lib/python2.7/site-packages/pandas/core/frame.pyc in _getitem_column(self, key)
   2002         # get column
   2003         if self.columns.is_unique:
-> 2004             return self._get_item_cache(key)
   2005 
   2006         # duplicate columns & possible reduce dimensionality

/home/edamame/anaconda2/lib/python2.7/site-packages/pandas/core/generic.pyc in _get_item_cache(self, item)
   1348         res = cache.get(item)
   1349         if res is None:
-> 1350             values = self._data.get(item)
   1351             res = self._box_item_values(item, values)
   1352             cache[item] = res

/home/edamame/anaconda2/lib/python2.7/site-packages/pandas/core/internals.pyc in get(self, item, fastpath)
   3288 
   3289             if not isnull(item):
-> 3290                 loc = self.items.get_loc(item)
   3291             else:
   3292                 indexer = np.arange(len(self.items))[isnull(self.items)]

/home/edamame/anaconda2/lib/python2.7/site-packages/pandas/indexes/base.pyc in get_loc(self, key, method, tolerance)
   1945                 return self._engine.get_loc(key)
   1946             except KeyError:
-> 1947                 return self._engine.get_loc(self._maybe_cast_indexer(key))
   1948 
   1949         indexer = self.get_indexer([key], method=method, tolerance=tolerance)

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4154)()

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12368)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12322)()

KeyError: True

或

my_df[my_df.editions != None]
my_df.shape

这个没有给出错误，但没有过滤掉任何 None 值。

我也试过:

my_df = my_df[my_df.editions.notnull()]

这个不会给出错误，但也不会过滤掉任何 None 值。

谁能告诉我如何解决这个问题？谢谢!

Answer 1

您可以在使用 ~ 过滤时否定条件。

所以在你的情况下你应该这样做:

my_df = my_df[~my_df.editions.isnull()]