r - switch 语句给出意外的 ',' 错误

Question

我正在尝试创建一个简单的开关来根据季度确定开始日期。

我的代码如下:

qtr_start <- function(qtr, yr){
  switch(qtr,
         1 = paste(yr, "0101", sep = ""),
         2 = paste(yr, "0104", sep = ""),
         3 = paste(yr, "0107", sep = ""),
         4 = paste(yr, "0110", sep = ""))
}

这给出了错误:

Error: unexpected '=' in:
"switch(qtr,
         1 ="
>          2 = paste(yr, "0104", sep = ""),
Error: unexpected ',' in "         2 = paste(yr, "0104", sep = ""),"
>          3 = paste(yr, "0107", sep = ""),
Error: unexpected ',' in "         3 = paste(yr, "0107", sep = ""),"
>          4 = paste(yr, "0110", sep = ""))
Error: unexpected ')' in "         4 = paste(yr, "0110", sep = ""))"

我真的很难看出这与帮助版本有何不同:

centre <- function(x, type) {
  switch(type,
         mean = mean(x),
         median = median(x),
         trimmed = mean(x, trim = .1))
}

感谢所有帮助!

Answer 1

您不能使用数字作为案例名称。把它们放在一边(R 将对 1 使用第一种情况，对 2 使用第二种情况，依此类推，或者使用字符串 [edit] 并使用 as.character 在号码上。

所以

 qtr_start <- function(qtr, yr){
     switch(qtr,
        paste(yr, "0101", sep = ""),
        paste(yr, "0104", sep = ""),
        paste(yr, "0107", sep = ""),
        paste(yr, "0110", sep = "")) }

或

qtr_start <- function(qtr, yr){
  switch(as.character(qtr),
         "1" = paste(yr, "0101", sep = ""),
         "2" = paste(yr, "0104", sep = ""),
         "3" = paste(yr, "0107", sep = ""),
         "4" = paste(yr, "0110", sep = ""))
}