[英]Attribute error applying a transform across a list of columns in a pandas dataframe
嗨,我有一个 dataframe 和一个我想执行循环的列列表:
#list of the 4 columns i want to perform function on
columnnames= ['a','b','c','d']
#Function
for col in columnnames:
df[f"{col}_new"] = df.groupby('Name')[col].transform(lambda x: x.rolling(20).apply(ewma).shift())
当我运行此循环时,我收到以下错误:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-21-519963825599> in <module>
8 ewma = partial(np.average, weights=weights)
9 for col in columnnames:
---> 10 df[f"{col}_new"] = df.groupby('Name')[col].transform(lambda x: x.rolling(20).apply(ewma).shift())
11
12 #df['testcolumn'] = df['test']*2
~\anaconda3\lib\site-packages\pandas\core\groupby\generic.py in transform(self, func, *args, **kwargs)
463
464 if not isinstance(func, str):
--> 465 return self._transform_general(func, *args, **kwargs)
466
467 elif func not in base.transform_kernel_whitelist:
~\anaconda3\lib\site-packages\pandas\core\groupby\generic.py in _transform_general(self, func, *args, **kwargs)
507 # we have a numeric dtype, as these are *always* user-defined funcs
508 # the cython take a different path (and casting)
--> 509 dtype = self._selected_obj.dtype
510 if is_numeric_dtype(dtype):
511 result = maybe_downcast_to_dtype(result, dtype)
~\anaconda3\lib\site-packages\pandas\core\generic.py in __getattr__(self, name)
5272 if self._info_axis._can_hold_identifiers_and_holds_name(name):
5273 return self[name]
-> 5274 return object.__getattribute__(self, name)
5275
5276 def __setattr__(self, name: str, value) -> None:
AttributeError: 'DataFrame' object has no attribute 'dtype'
关于我的问题可能是什么的任何想法?
我已经在不同的 dataframe (非常相似)上成功运行了这个,所以我只是不知道这个错误告诉我什么。
非常感谢!
原来我的错误是我有一些同名的列!
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