為什么此代碼在 pandas 中引發錯誤？

Question

我在 Stepik 上解決了這個問題：名為 my_stat 的數據框包含 4 列數據：session_value、group、time、n_users。 在變量 n_users 中，我們將所有負值替換為 n_users 的中值（當然不包括負值）。 這是我寫的（我是熊貓的新手）：

import pandas as pd    
import numpy as np

my_stat = my_stat['session_value'].replace(np.nan, 0)
my_stat.loc[my_stat['n_users'] < 0, 'n_users'] = my_stat['n_users'].median()

但是在發布回復時，我收到此錯誤：

Error:
Traceback (most recent call last):
  File "jailed_code", line 25, in <module>
    med = my_stat['n_users'].median()
  File "/home/stepic/instances/master-plugins/sandbox/python3/lib/python3.6/site-packages/pandas/core/series.py", line 871, in __getitem__
    result = self.index.get_value(self, key)
  File "/home/stepic/instances/master-plugins/sandbox/python3/lib/python3.6/site-packages/pandas/core/indexes/base.py", line 4405, in get_value
    return self._engine.get_value(s, k, tz=getattr(series.dtype, "tz", None))
  File "pandas/_libs/index.pyx", line 80, in pandas._libs.index.IndexEngine.get_value
  File "pandas/_libs/index.pyx", line 90, in pandas._libs.index.IndexEngine.get_value
  File "pandas/_libs/index.pyx", line 135, in pandas._libs.index.IndexEngine.get_loc
  File "pandas/_libs/index_class_helper.pxi", line 109, in pandas._libs.index.Int64Engine._check_type
KeyError: 'n_users'

如何解決？

Answer 1

改變你的線路

my_stat = my_stat['session_value'].replace(np.nan, 0)

對此

my_stat['session_value'] = my_stat['session_value'].replace(np.nan, 0)