为什么在 Pandas 中选择具有逻辑语句的行时，我必须指定 dataframe 两次？

Question

I'm not sure what the reason might be for having to specify the name of the dataframe twice when selecting rows using conditional statements in Pandas. For example, if I have a dataframe df :

name	age
Alice	31
Bob	21

when I want to select rows with people over 30 I have to write over_thirty = df[df.age > 30] . Why not simply df['age' > 30]] ?

Answer 1

Use .query

over_thirty = df.query("age > 30")

Answer 2

so if you write df[age>3] it will give you output in true or false. I am sure which you not needed