无法将字符串转换为浮点对象类型

Question

我正在使用Pandas和Jupyter Notebook使用Python中的数据框，我的数据框具有经度和纬度列，值为'-23,4588'。不知何故，每次我试图将其转换为float，我得到一个错误告诉'could not convert string to float'。

我试图改变逗号，试图改变。csv列类型为浮动，但没有工作。

我的一部分代码:

ValueError                                Traceback (most recent call last)
C:TEMP/ipykernel_12640/4061618161.py in <module>
----> 1 newocorr_sjc['Latitude'] = newocorr_sjc['Latitude'].astype(float)
c:userscaique.fernandesappdatalocalprogramspythonpython39libsite-packagespandascoregeneric.py in astype(self, dtype, copy, errors)
5875         else:
5876             # else, only a single dtype is given
-> 5877             new_data = self._mgr.astype(dtype=dtype, copy=copy, errors=errors)
5878             return self._constructor(new_data).__finalize__(self, method="astype")
5879 
c:userscaique.fernandesappdatalocalprogramspythonpython39libsite-packagespandascoreinternalsmanagers.py in astype(self, dtype, copy, errors)
629         self, dtype, copy: bool = False, errors: str = "raise"
630     ) -> "BlockManager":
--> 631         return self.apply("astype", dtype=dtype, copy=copy, errors=errors)
632 
633     def convert(
c:userscaique.fernandesappdatalocalprogramspythonpython39libsite-packagespandascoreinternalsmanagers.py in apply(self, f, align_keys, ignore_failures, **kwargs)
425                     applied = b.apply(f, **kwargs)
426                 else:
--> 427                     applied = getattr(b, f)(**kwargs)
428             except (TypeError, NotImplementedError):
429                 if not ignore_failures:
c:userscaique.fernandesappdatalocalprogramspythonpython39libsite-packagespandascoreinternalsblocks.py in astype(self, dtype, copy, errors)
671             vals1d = values.ravel()
672             try:
--> 673                 values = astype_nansafe(vals1d, dtype, copy=True)
674             except (ValueError, TypeError):
675                 # e.g. astype_nansafe can fail on object-dtype of strings
c:userscaique.fernandesappdatalocalprogramspythonpython39libsite-packagespandascoredtypescast.py in astype_nansafe(arr, dtype, copy, skipna)
1095     if copy or is_object_dtype(arr) or is_object_dtype(dtype):
1096         # Explicit copy, or required since NumPy can't view from / to object.
-> 1097         return arr.astype(dtype, copy=True)
1098 
1099     return arr.view(dtype)
ValueError: could not convert string to float: '-23,5327'```

Answer 1

也许你应该使用decimal=','作为pd.read_csv的参数:

df = pd.read_csv('data.csv', sep=';', decimal=',')

>>> df.select_dtypes(float)
17       22       23
0  17.5 -23.5327 -46.8182
1  56.3 -23.4315 -47.1269