R 中的自定义函数

Question

我正在尝试写一个问候 function，它需要两个 arguments，一个时间和一个名字，并根据一天中的时间说“早上好”、“下午好”或“晚上好”。

我还想使用lubridate::now()作为 time 参数的默认值。 但不确定这是正确的做法还是有更好的选择？

greet <- function(time = lubridate::now(), name) {
  hour <- parse_number(str_sub(time, 12, 13))
  if (hour < 12) {
    cat("good morning", name)
  } else if (hour < 17) {
    cat("good afternoon", name)
  } else {
    cat("good evening", name)
  }
}

#sanity check

greet(name = "User 1")
#> [1] "good afternoon User 1"
greet(ymd_h("2021-03-31 05"), "User 2")
#> [1] "good morning User 2"
greet(ymd_h("2021-03-31 13"), "User 3")
#> [1] "good afternoon User 3"
greet(ymd_h("2021-03-31 20"), "User 4")
#> [1] "good evening User 4"

Answer 1

greet <- function(time = lubridate::now(), name) {
  hour <- parse_number(str_sub(time, 12, 13))
  if(hour < 0 || hour > 23) {
    stop("Please define a correct time")
  }
  if (hour < 12) {
    cat("good morning", name)
  } else if (hour < 17) {
    cat("good afternoon", name)
  } else {
    cat("good evening", name)
  }
}

greet("2020-01-01 25:45:32", "User 5")
greet("2020-01-01 -1:45:32", "User 5")