r - 如何从 POSIXct 时间戳向量在 R 中创建日期部分？

Question

我有一长串 POSIXct 时间戳。我想返回每个记录的一天部分，包括一周中的某一天。 例如:

[1] Sunday night
[2] Sunday night
[3] Sunday afternoon
[4] Saturday night
[5] Sunday afternoon

...等等。

以下是一小部分数据示例:

my_dates <- as.POSIXct(c("2000-03-12 19:40:00 AEDT",
                            "2000-03-19 17:40:00 AEDT", 
                            "2000-03-26 14:10:00 AEST", 
                            "2000-04-01 19:40:00 AEST", 
                            "2000-04-09 14:10:00 AEST",
                            "2000-04-16 14:40:00 AEST",
                            "2000-04-22 19:40:00 AEST",
                            "2000-04-30 14:10:00 AEST",
                            "2000-05-07 14:10:00 AEST",
                            "2000-05-14 14:10:00 AEST"))

我尝试了很多不同的方法，但最终总是丢失日期格式。

任何帮助将不胜感激。 谢谢

Answer 1

一些有创意的格式设置和剪切设置应该能够帮助您实现目标:

paste(
  format(my_dates, "%A"),
  c("night","morn","afternoon","night")[
    cut(as.numeric(format(my_dates,"%H")), c(0,5,11,17,23))
  ]
)
# [1] "Sunday night"     "Sunday afternoon" "Sunday afternoon" "Saturday night"  
# [5] "Sunday afternoon" "Sunday afternoon" "Saturday night"   "Sunday afternoon"
# [9] "Sunday afternoon" "Sunday afternoon"