R语言中如何抽取向量的偶数项或者奇数项

 

 

001、 R语言中如何抽取向量的偶数项或者奇数项

> a <- letters[1:10]                          ## 生成一个测试向量
> a
 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j"
> a[seq(1, length(a), 2)]                     ## 提取奇数项
[1] "a" "c" "e" "g" "i"
> a[seq(2, length(a), 2)]                     ## 提取偶数项
[1] "b" "d" "f" "h" "j"

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