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r - 切换功能？

问题描述

大家好，我有一个数据框，其中有一列“day”，其中包含从 1 到 100 的序数。如何创建一个函数来将日期数字转换为日期名称

标签： r

解决方案

您可以switch使用sapply：

covertdays <- function(x) {c("Monday", "Tuesday", "Wednesday", "Thursday",
  "Friday", "Saturday", "Sunday")[(x-1) %% 7 + 1]}
covertdays(1:100)
#  [1] "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday" 
#  [7] "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"   
# [13] "Saturday"  "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday" 
# [19] "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"   "Wednesday"
# [25] "Thursday"  "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"  
# [31] "Wednesday" "Thursday"  "Friday"    "Saturday"  "Sunday"    "Monday"   
# [37] "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday"  "Sunday"   
# [43] "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday" 
# [49] "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"   
# [55] "Saturday"  "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday" 
# [61] "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"   "Wednesday"
# [67] "Thursday"  "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"  
# [73] "Wednesday" "Thursday"  "Friday"    "Saturday"  "Sunday"    "Monday"   
# [79] "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday"  "Sunday"   
# [85] "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday" 
# [91] "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"   
# [97] "Saturday"  "Sunday"    "Monday"    "Tuesday"

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