如何在R中选择列表的多个元素？
通常，R中的列表包含大量元素，每个元素可以具有不同的类型，这对于列表来说是一件好事。由于我们可以将数据类型存储为列表元素，因此存储和选择不同类型的数据变得更加容易。我们还可以一次选择列表中的单个或多个元素。这可以借助单个方括号来完成。
示例
请看以下列表-
> list_data <- list("India", "China", c(21,32,11), letters[1:5], TRUE,
+ 12, letters[-c(1:10)], c(100,101,200,201), "USA", c("Asia", "Europe"),
+ "Education", "Poverty", "Covid-19", 365, 12, 24, 60, 7)
> list_data
[[1]]
[1] "India"
[[2]]
[1] "China"
[[3]]
[1] 21 32 11
[[4]]
[1] "a" "b" "c" "d" "e"
[[5]]
[1] TRUE
[[6]]
[1] 12
[[7]]
[1] "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"
[[8]]
[1] 100 101 200 201
[[9]]
[1] "USA"
[[10]]
[1] "Asia" "Europe"
[[11]]
[1] "Education"
[[12]]
[1] "Poverty"
[[13]]
[1] "Covid-19"
[[14]]
[1] 365
[[15]]
[1] 12
[[16]]
[1] 24
[[17]]
[1] 60
[[18]]
[1] 7选择list_data的不同元素-
> list_data[c(1,2,3)] [[1]] [1] "India" [[2]] [1] "China" [[3]] [1] 21 32 11 > list_data[c(18,2,3)] [[1]] [1] 7 [[2]] [1] "China" [[3]] [1] 21 32 11 > list_data[c(1,15,18)] [[1]] [1] "India" [[2]] [1] 12 [[3]] [1] 7 > list_data[c(5,10,15)] [[1]] [1] TRUE [[2]] [1] "Asia" "Europe" [[3]] [1] 12 > list_data[c(7,3,10)] [[1]] [1] "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" [[2]] [1] 21 32 11 [[3]] [1] "Asia" "Europe"