获取具有对象或分类数据类型的列名列表 [英] Get list of column names having either object or categorical dtype

问题描述

我的目标是获取一个列表对象:['assetCode', 'assetName']，其中的内容是检索到的 Panda.series 的标签基于一个以上的条件.我试过了:

My goal is to get a list object: ['assetCode', 'assetName'], where the contents are the labels of a Panda.series that are retrieved based on more than one condition. I tried:

tmp3 = datatype[datatype == 'object' | datatype == 'category'].index # extract label from Pandas.series

这给出了错误:TypeError: cannot compare a dtyped [object] array with a scalar of type [bool]

然而，虽然不太优雅，但我能够找到以下两个可行的解决方案:

However, while less elegant, I was able to find the following two working solutions:

tmp2 = datatype[datatype == 'object'].index # extract label from Pandas.series
tmp2[0]
'assetCode'


tmp1 = datatype[datatype == 'category'].index # extract label from Pandas.series
tmp1[0]
'assetName'

如何将这两个字符串组合成一个列表对象?有没有比我尝试的方式更好的方法来实现这个目标?

How do I combine these two strings into a list object? Is there a better way to achieve that goal than the way I am trying to do it?

推荐答案

设置

df

   A  B  C
0  8  4  2
1  8  8  6
2  8  5  2

datatype = df.dtypes
datatype

A      object
B    category
C       int64
dtype: object

<小时>

您似乎正在尝试从某个 DataFrame(此处未显示)中选择对象和分类列.要修复您的代码，请使用:

---

It looks like you are trying to select object and categorical columns from some DataFrame (not shown here). To fix your code, use:

tmp3 = datatype[(datatype == 'object') | (datatype == 'category')].index.tolist()
tmp3
#  ['A', 'B']

由于按位运算符具有更高的优先级，您需要在对掩码进行 OR 运算之前使用括号.之后，索引工作正常.

Since bitwise operators have higher precedence, you will need to use parentheses before ORing the masks. After that, indexing works fine.

要获取列表，请调用 .index.tolist().

To get a list, call .index.tolist().

另一个解决方案是select_dtypes:

df.select_dtypes(include=['object', 'category'])

   A  B
0  8  4
1  8  8
2  8  5

df.select_dtypes(include=['object', 'category']).columns
# ['A', 'B']

这避免了对中间datatype系列的需求.

This circumvents the need for an intermediate datatype series.

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