I have a data frame which looks like this:
(我有一个数据框架，看起来像这样：)
"22:36:59", "22:37:00", "22:37:01", "22:37:02", "22:37:03", "23:47:39", "23:47:40", "23:47:41", "23:47:42", "23:47:43", "23:47:44", "23:47:45", "23:47:46", "23:47:47", "23:47:48", "23:59:49", "23:59:50", "23:59:51", "23:59:52", "23:59:53", "23:59:54", "23:59:55", "23:59:56", "23:59:57", "23:59:58", "23:59:59"), class = "factor"), V5 = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "CEST", class = "factor"), V6 = c(2019L, 2019L, 2019L, 2019L, 2019L, 2019L, 2019L, 2019L, 2019L, 2019L)), row.names = c(NA, 10L), class = "data.frame") I want to change the hours in column V4 by subtracting 07:00:00.
(“ 22:36:59”，“ 22:37:00”，“ 22:37:01”，“ 22:37:02”，“ 22:37:03”，“ 23:47:39”，“ 23 ：47：40“，” 23:47:41“，” 23:47:42“，” 23:47:43“，” 23:47:44“，” 23:47:45“，” 23:47 ：46“，” 23:47:47“，” 23:47:48“，” 23:59:49“，” 23:59:50“，” 23:59:51“，” 23:59:52 “，” 23:59:53“，” 23:59:54“，” 23:59:55“，” 23:59:56“，” 23:59:57“，” 23:59:58“， “ 23:59:59”），类=“因子”），V5 =结构（c（1L，1L，1L，1L，1L，1L，1L，1L，1L，1L），.Label =“ CEST”， class =“ factor”），V6 = c（2019L，2019L，2019L，2019L，2019L，2019L，2019L，2019L，2019L，2019L）），row.names = c（NA，10L），class =“ data.frame “）我想通过减去07:00:00来更改V4列中的小时。)
If the hours in column V4 is smaller than 07:00:00 then it should as well change the day in column V3 and in case the day goes to the month before then it should change the month in column V2. (如果V4列中的小时数小于07:00:00，则还应更改V3列中的日期，并且如果该日期到达前一个月，则应更改V2列中的月份。)
The final aim of this is to count how many rows are there for each day, for which I can use: count(entertainment_one, c("V2", "V3")) but before I need to reorganise my data frame. (这样做的最终目的是计算每天可以使用多少行：count（entertainment_one，c（“ V2”，“ V3”））但在我需要重新组织数据框之前。)
I am new to R and do not know where to start. (我是R新手，不知道从哪里开始。)
Any help would be really appreciated, thank you very much! (任何帮助将不胜感激，非常感谢！)
ask by Sofia Olivieri translate from so 
