这是一个使用正则表达式的 sub 解决方案:

Here's a sub solution using a regular expression:

set.seed(1); times <- paste0(sample(0:23,10), sample(0:59,10)) # ex. data
sub("(\\d+)(\\d{2})", "\\1:\\2", times) # put in delimitter
# [1] "6:12"  "8:10"  "12:39" "19:21" "4:43"  "17:27" "18:38" "11:52" "10:19" "0:57"