r - r中具有多个条件的switch语句

Question

我想在 r 中用三个条件编写一个 switch 语句，但似乎无法让它工作。我做错了什么？

# assigning some values
test.type <- "p"
var.equal<- TRUE
  paired <- FALSE

# preparing text for which p-value adjustment method was used
test.description <- switch(
    EXPR = test.type & var.equal & paired,
    "p" & TRUE & TRUE = "Student's t-test",
    "p" & FALSE & TRUE = "Student's t-test",
    "p" & TRUE & FALSE = "Student's t-test",
    "p" & FALSE & FALSE = "Games-Howell test",
    "np" & TRUE & TRUE = "Durbin-Conover test"
  )
#> Error: <text>:10:23: unexpected '='
#> 9:     EXPR = test.type & var.equal & paired,
#> 10:     "p" & TRUE & TRUE =
#>                           ^

^{由 reprex package 创建于 2018-11-08 (v0.2.1)}

只有一个条件的此语句的更简单版本可以工作-

# simpler switch
(test.description <- switch(
  EXPR = test.type,
  "p"  = "Student's t-test",
  "np" = "Durbin-Conover test"
))
#> [1] "Student's t-test"

^{由 reprex package 创建于 2018-11-08 (v0.2.1)}

Answer 1

另一种解决方案可能是使用 dplyr 的 case_when，它使用的语法更类似于您的 switch 语句:

library(dplyr)

## initial dataframe
df <- data.frame(
  test.type = c("p", "p", "p", "p", "np", "np"),
  var.equal = c(TRUE, FALSE, TRUE, FALSE, TRUE, FALSE),
  paired = c(TRUE, TRUE, FALSE, FALSE, TRUE, FALSE)
  ) 

## add column test.description 
mutate(df,
  test.description = case_when(
      test.type == "p" & !var.equal & !paired  ~ "Games-Howell test",
      test.type == "p"                         ~ "Student's t-test",
      test.type == "np" & var.equal & paired   ~ "Durbin-Conover test",
      TRUE                                     ~ "Unknown combination"
     )
)