r - 如何连接字符串和从 R 中的函数评估的输出？

Question

基本上，我有以下说法：

counter <- 3
k <- 9999

我想让 R 打印以下内容：

on the 3rd count: 9999 

有谁我应该使用什么命令来做到这一点？请为我拼写出来，因为我对 R 完全陌生。

Answer 1

基本结构是

paste("on the ", counter, "rd count: ", k, sep="")

您必须有点聪明才能为数字选择正确的后缀（即 3 后的“rd”，4-9 后的“th”等。这是一个功能：

suffixSelector <- function(x) {
  if (x%%10==1) {
    suffixSelector <- "st"
  } else if(x%%10==2) {
    suffixSelector <- "nd"
  } else if(x%%10==3) {
    suffixSelector <- "rd"
  } else {
    suffixSelector <- "th"
  }

}

因此：

suffix <- suffixSelector(counter)
paste("on the ", counter, suffix, " count: ", k, sep="")

您需要设置sep参数，因为默认情况下paste会在字符串之间插入一个空格。

Answer 2

采用sprintf

> sprintf("on the %drd count: %d", counter, k)
[1] "on the 3rd count: 9999"

Answer 3

这是一种将每个整数与适当的后缀挂钩的稍微不同的方法。如果你把它分开，你会发现它确实捕获了构造每个整数的序数形式的句法（？）规则。

suffixPicker <- function(x) {
    suffix <- c("st", "nd", "rd", rep("th", 17))
    suffix[((x-1) %% 10 + 1) + 10*(((x %% 100) %/% 10) == 1)]
}

## Testing with your example
counter <- 3
k <- 9999
paste("on the ", paste0(counter, suffixPicker(counter)), 
      " count: ", k, sep="")
# [1] "on the 3rd count: 9999"

## Show that it also works for a range of numbers
x <- 1:24
paste0(x, suffixPicker(x))
#  [1] "1st"  "2nd"  "3rd"  "4th"  "5th"  "6th"  "7th"  "8th"  "9th"  "10th"
# [11] "11th" "12th" "13th" "14th" "15th" "16th" "17th" "18th" "19th" "20th"
# [21] "21st" "22nd" "23rd" "24th"

一个解释性说明：需要该10*(((x %% 100) %/% 10) == 1)位来挑选以 10 到 19 结尾的数字（11、12 和 13 是这里真正的坏演员）将它们全部发送到 contains 的suffix元素"th"。