import pandas as pd
df = pd.read_excel(r'C:\Users\Administrator\Desktop\时间安排.xlsx')
df = df['date']
.......
请问大神们
df['date'] 是一个列索引，他底层是怎么实现的？是调用DataFrame类里面的哪一个方法实现的？
应该是__getitem__方法。
我是去访问不存在的列索引 或者 访问行索引，看报错信息。
df = pd.DataFrame(
data=[0,1,2,3],
index=list('ABCD'),
columns=['col']
)
df['E']
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
/usr/local/lib/python3.7/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
3080 try:
-> 3081 return self._engine.get_loc(casted_key)
3082 except KeyError as err:
pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()
pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()
pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()
pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()
KeyError: 'E'
The above exception was the direct cause of the following exception:
KeyError Traceback (most recent call last)
<ipython-input-61-da103df23740> in <module>
----> 1 df['E']
/usr/local/lib/python3.7/site-packages/pandas/core/frame.py in __getitem__(self, key)
3022 if self.columns.nlevels > 1:
3023 return self._getitem_multilevel(key)
-> 3024 indexer = self.columns.get_loc(key)
3025 if is_integer(indexer):
3026 indexer = [indexer]
/usr/local/lib/python3.7/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
3081 return self._engine.get_loc(casted_key)
3082 except KeyError as err:
-> 3083 raise KeyError(key) from err
3084
3085 if tolerance is not None:
KeyError: 'E'