r - 更改 R 中向量中元素的顺序

Question

我有一个包含某行元素的向量，但现在我想更改这些元素的顺序。我怎样才能只用一行代码做到这一点？

# 1.create queue

queue <- c("James", "Mary", "Steve", "Alex", "Patricia")
queue

# 2.move Patricia to be in front of Steve

???

我是 R 的初学者，所以让你的回答尽可能简单和淡化!谢谢!

Answer 1

我的 moveMe function (在 my SOfun package 中)非常适合这个。加载包后，您可以执行以下操作:

library(SOfun)
queue <- c("James", "Mary", "Steve", "Alex", "Patricia")
moveMe(queue, "Patricia before Steve")
# [1] "James"    "Mary"     "Patricia" "Steve"    "Alex"  

您还可以通过用分号分隔来复合命令:

moveMe(queue, "Patricia before Steve; James last")
# [1] "Mary"     "Patricia" "Steve"    "Alex"     "James" 

moveMe(queue, "Patricia before Steve; James last; Mary after Alex")
# [1] "Patricia" "Steve"    "Alex"     "Mary"     "James" 

移动选项包括:“first”、“last”、“before”和“after”。

您还可以通过用逗号分隔多个值来将多个值移动到一个位置。例如，要将“Patricia”和“Alex”移动到“Mary”之前(按该顺序重新排序)，然后将“Steve”移动到队列的开头，您可以使用:

moveMe(queue, "Patricia, Alex before Mary; Steve first")
# [1] "Steve"    "James"    "Patricia" "Alex"     "Mary"  

您可以使用以下命令安装 SOFun:

library(devtools)
install_github("SOfun", "mrdwab")

对于在另一个值之前移动的单个值，您还可以采用如下方法:

## Create a vector without "Patricia"
x <- setdiff(queue, "Patricia")
## Use `match` to find the point at which to insert "Patricia"
## Use `append` to insert "Patricia" at the relevant point
x <- append(x, values = "Patricia", after = match("Steve", x) - 1)
x
# [1] "James"    "Mary"     "Patricia" "Steve"    "Alex"