Question

我有一个数据集，其中列中有3列名为CLASS，DURATION和GENDER。

import pandas as pd
data = pd.read_csv('dataset.csv')
CLASS = data['CLASS']
DURATION = data['DURATION']
GENDER = data['GENDER']

CLASS包含5种类型的条目 - blank, 1, 2, 3, 4; DURATION包含-1（表示某些语义值）或某个正整数; GENDER包含M或F。我可以按CLASS选择GENDER中的条目，如下所示：

CLASS[GENDER=='M']

但我无法在OCCUP_CLASS中选择-1的持续时间，如下所示：

CLASS[DURATION=='-1']

为什么？这是我得到的错误：

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-56-604aed5ebca4> in <module>()
----> 1 CLASS[DURATION=='-1']

c:\users\h473\appdata\local\programs\python\python35\lib\site-packages\pandas\core\series.py in __getitem__(self, key)
    621         key = com._apply_if_callable(key, self)
    622         try:
--> 623             result = self.index.get_value(self, key)
    624 
    625             if not is_scalar(result):

c:\users\h473\appdata\local\programs\python\python35\lib\site-packages\pandas\core\indexes\base.py in get_value(self, series, key)
   2558         try:
   2559             return self._engine.get_value(s, k,
-> 2560                                           tz=getattr(series.dtype, 'tz', None))
   2561         except KeyError as e1:
   2562             if len(self) > 0 and self.inferred_type in ['integer', 'boolean']:

pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_value()

pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_value()

pandas\_libs\index_class_helper.pxi in pandas._libs.index.Int64Engine._check_type()

pandas\_libs\index_class_helper.pxi in pandas._libs.index.Int64Engine._check_type()

KeyError: False

Answer 1

我无法复制，但你可以尝试

import pandas as pd
data = pd.read_csv('dataset.csv')
CLASS = data['CLASS']
DURATION = data['DURATION']
GENDER = data['GENDER']

# fill the nan value 
DURATION.fillna(0,inplace=True)
# using astype convert the value to int then compare
CLASS[DURATION].astype(int)>0

Answer 2

也许最好不要将它们拆分为系列开始，而是在Dataframe上尝试这个：

import pandas as pd
data = pd.read_csv('dataset.csv')
data.loc[data['GENDER'] == 'M', 'CLASS']
data.loc[data['DURATION'] == -1, 'CLASS']

为什么我无法从按其他列表中的元素过滤的列表中选择某些元素？

2 个答案: