Question

我有一个相对较大的数据框。我试图遍历每一行并根据特定的列值更新一列（基本上是尝试循环查找，直到无法更新其他列为止）

我有以下内容：

df = the huge dataframe (1K to 10K+ rows x 51 cols)

has_update = True
while has_update:
   has_update = False

   for_procdf = df.loc[df['Incident Group ID'] == '-']

   for i, row in for_procdf.iterrows():
       #Check if the row's parent ticket id is an existing ticket id in the bigger df
       resultRow = df.loc[df['Ticket ID'] == row['Parent Ticket ID']]
       resultCount = len(resultRow.index)
       if resultCount == 1:
           IncidentGroupID = resultRow.iloc[0]['Incident Group ID']
           if IncidentGroupID != '-':
               df.at[i, "Incident Group ID"] = IncidentGroupID
               has_update = True

执行脚本时，发生以下回溯错误：

Traceback (most recent call last):
  File "./sdm.etl.py", line 76, in <module>
    main()
  File "./sdm.etl.py", line 28, in main
    fillIncidentGroupID(sdmdf.df)
  File "./sdm.etl.py", line 47, in fillIncidentGroupID
    df.at[i, "Incident Group ID"] = IncidentGroupID
  File "/usr/local/lib/python3.6/site-packages/pandas/core/indexing.py", line 2159, in __setitem__
    self.obj._set_value(*key, takeable=self._takeable)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/frame.py", line 2580, in _set_value
    series = self._get_item_cache(col)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/generic.py", line 2490, in _get_item_cache
    res = self._box_item_values(item, values)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/frame.py", line 3096, in _box_item_values
    return self._constructor(values.T, columns=items, index=self.index)
AttributeError: 'BlockManager' object has no attribute 'T'

但是创建类似方案不会返回错误

>>> qdf = pd.DataFrame([[0, 2, 3], [0, 4, 1], [10, 20, 30], [10, 13, 17]], index=[0,1,2,3], columns=['Ab 1', 'Bc 2', 'Cd 3'])
>>> qdf
   Ab 1  Bc 2  Cd 3
0     0     2     3
1     0     4     1
2    10    20    30
3    10    13    17
>>>
>>> qdf1 = qdf.loc[qdf['Ab 1'] == 0]
>>> qdf1
   Ab 1  Bc 2  Cd 3
0     0     2     3
1     0     4     1
>>>
>>> for i, row in qdf1.iterrows():
...     qdf.at[i, 'Ab 1'] = 10
...
>>>
>>> qdf
   Ab 1  Bc 2  Cd 3
0    10     2     3
1    10     4     1
2    10    20    30
3    10    13    17

我的实现似乎有什么问题？

Answer 1

发现Nihal是正确的，该错误是由重复的列名引起的。我的数据框太大，以至于我不小心有重复的列名。现在一切正常。离代码有点时间，休息和吃东西使我看到重复的列。干杯！

下面是我的数据框的列。 “ RCA组ID” 在结尾附近重复。

['Incident Group ID', 'RCA Group ID', 'Parent Ticket ID', 'Ticket ID', ..., 'RCA Group ID', 'Is Sector Down', 'Relationship Type']

Answer 2

该错误是由重复的列名引起的

在我的情况下是这样。

您可以使用以下功能快速确定哪些列名称重复。

def get_duplicate_cols(df: pd.DataFrame) -> pd.Series:
    return pd.Series(df.columns).value_counts()[lambda x: x>1]

Source

熊猫df.at（）引发AttributeError：'BlockManager'对象没有属性'T'

2 个答案: