R来自数据帧的行选择向量

Question

I want to implement a simple row selection vector using the 'country' column on the below lat_all data frame in R.

pop   country      lat
12.4  Afghanistan  62
24.3  Australia    12
4     New Zealand  10
100   Japan        30
12    Fiji         28

Using a selection below which I can change easily such as

selection <- c("Afghanistan","Australia","Japan")

I want the result to be:

        pop            country       lat
1      12.4        Afghanistan       62
2      24.3          Australia       12
4       100              Japan       30

Only way I can get what I want so far is using the below which doesn't use the selection vector

lat_all[ lat_all[2]==("Afghanistan") | lat_all[2]==("Australia") | lat_all[2]==("Japan"), ]

I don't understand why something like lat_all[2]==selection doesn't work for me. The selection vector only finds Afghanistan and Japan. Australia is FALSE and any output using that vector skips Australia.

Answer 1

use subset function

lat_all  <- subset(lat_all, country %in% selection)