我如何解释这个符号? [英] How do I interpret this notation?

问题描述

符号 s[s] 如何以及为什么起作用?

How and why does the notation s[s] work?

我正在学习 kaggle.com 上的其中一门微课程，它们使用符号 s[s]，如下所示.我以前没见过.X_train 是一个 Pandas DataFrame.

I'm taking one of the micro-courses from kaggle.com and they use the notation s[s] as shown below. I have not seen that before. X_train is a pandas DataFrame.

它是一个自我切片的列表吗?有人能帮忙澄清一下吗?

Is it a list slicing itself? Would someone help clarify this?

s = (X_train.dtypes == 'object') ## assigns True to variables == 'object'
object_cols = list(s[s].index)

> s

Type              True
Method            True
Regionname        True
Rooms            False
Distance         False
Postcode         False
Bedroom2         False
Bathroom         False
Landsize         False
Lattitude        False
Longtitude       False
Propertycount    False
dtype: bool

> s[s]

Type          True
Method        True
Regionname    True
dtype: bool

推荐答案

Pandas DataFrames 允许您索引使用布尔数组 这就是 s 在 [] 中的使用方式.如您所见，系列的值是 True 或 False，因此我们选择 s 的值，其中 s 是 True.此代码的目的是获取数据类型为 object 的列，您可以使用函数 pandas.DataFrame.select_dtypes 代替:

Pandas DataFrames allow you to index using boolean arrays which is how s is being used inside []. The value of the Series is True or False as you can see, so we're selecting the values of s where s is True. The purpose of this code is to get columns where the datatype is object, you can do it with the function pandas.DataFrame.select_dtypes instead:

list(X_train.select_dtypes(include=['object']).columns)

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