基础 R 中是否有一种快速方法可以根据操作关系对数据帧进行子集化？ （例如 MPG >20）

Question

I am sure this can be handled much easier with packages such as Tidyverse. However, I am trying to solve it by just simply using base R. To illustrate the problem I've used the "mtcars" dataset.

Example: Subset only for cars with MPG > 20

1.) first intuition of mine was to try the following:

mtcars[mtcars$mpg>20]

Which, rather unsurprisingly, does not work.

2.) Second, I've realized that I get an output when using:

mtcars$mpg[mtcars$mpg>20]
[1] 21.0 21.0 22.8 21.4 24.4 22.8 32.4 30.4 33.9 21.5 27.3 26.0 30.4 21.4

3.) This is not what I want though - I want keep the whole DF so I did the following:

mtcars$mpg>20 #gives me the Boolean values TRUE, FALSE 
mtcars$newcolum <- mtcars$mpg>20 #creating a new column 
subset(mtcars, newcolum==TRUE) #subsetting 

This leads to the subsetted data frame I intended to extract. However, it feels like this is quite tedious and I am overcomplicating the steps. Do you have any helpful advice on how the same output could be achieved faster?

Thank you very much! Chris

Answer 1

Subsetting in R requires both rows an columns so you can use , :

#Code
new <- mtcars[mtcars$mpg>20,]