カウントの要因が等間隔になる方法は？

Question

私が始めて30分の休憩で時間間隔を作成するために、いくつかの困難を持っているいずれかのフル時間00または完全な時間の00と30分で：例えば

：

library(reshape2) 
    library(dplyr) 

    # Given some data which resemble the original data 
    foo <- data.frame(start.time = c("2012-02-01 13:47:00", 
            "2012-02-01 14:02:00", 
            "2012-02-01 14:20:00", 
            "2012-02-01 14:40:00", 
            "2012-02-01 15:08:00", 
            "2012-02-01 16:01:00", 
            "2012-02-01 16:02:00", 
            "2012-02-01 16:20:00", 
            "2012-02-01 17:09:00", 
            "2012-02-01 18:08:00", 
            "2012-02-01 18:20:00", 
            "2012-02-01 19:08:00" 



            ), 
         employee = c("mike","john","john","steven","mike","mike","mike","steven","mike","steven","mike","mike")) 


          start.time employee 
      #1 2012-02-01 13:47:00  mike 
      #2 2012-02-01 14:02:00  john 
      #3 2012-02-01 14:20:00  john 
      #4 2012-02-01 14:40:00 steven 
      #5 2012-02-01 15:08:00  mike 
      #6 2012-02-01 16:01:00  mike 
      #7 2012-02-01 16:02:00  mike 
      #8 2012-02-01 16:20:00 steven 
      #9 2012-02-01 17:09:00  mike 
      #10 2012-02-01 18:08:00 steven 
      #11 2012-02-01 18:20:00  mike 
      #12 2012-02-01 19:08:00  mike 




    # change factor to POSIXct 
    foo$start.time <- as.POSIXct(foo$start.time) 
    # long to wide 
    my_emp<- dcast(foo, start.time ~ employee, fun.aggregate = length) 
    # 30 min breaks 
    my_emp_ag<- my_emp %>% group_by(start.time = as.POSIXct(cut(start.time, breaks="30 min"))) %>% 
     summarize(john = sum(john),mike = sum(mike),steven = sum(steven)) 
    # Missing intervalls 
    miss_interval <- data.frame(start.time=seq(from = min(as.POSIXct(my_emp$start.time)), to= max(as.POSIXct(my_emp$start.time)), by = "30 mins")) 

    # join old woth new 
    substitited <- left_join(miss_interval,my_emp_ag,by=c('start.time')) 
    # change NA to zero 
    substitited[is.na(substitited)] <- 0 

           start.time john mike steven 
        1 2012-02-01 13:47:00 1 1  0 
        2 2012-02-01 14:17:00 1 0  1 
        3 2012-02-01 14:47:00 0 1  0 
        4 2012-02-01 15:17:00 0 0  0 
        5 2012-02-01 15:47:00 0 2  0 
        6 2012-02-01 16:17:00 0 0  1 
        7 2012-02-01 16:47:00 0 1  0 
        8 2012-02-01 17:17:00 0 0  0 
        9 2012-02-01 17:47:00 0 0  1 
        10 2012-02-01 18:17:00 0 1  0 
        11 2012-02-01 18:47:00 0 1  0 

2012-02-01 13:30:00を必要に応じて、ほとんどです2012-02-01 14:00:00など。

Answer 1

library(data.table) 
library(lubridate) 

setDT(foo)[, `:=` (
    round.time = { 
    todate = ymd_hms(start.time) 
    rounddate = floor_date(todate, "30 minutes") 
    } 
)] 


      start.time employee   round.time 
1: 2012-02-01 13:47:00  mike 2012-02-01 13:30:00 
2: 2012-02-01 14:02:00  john 2012-02-01 14:00:00 
3: 2012-02-01 14:20:00  john 2012-02-01 14:00:00 
4: 2012-02-01 14:40:00 steven 2012-02-01 14:30:00 
5: 2012-02-01 15:08:00  mike 2012-02-01 15:00:00 
6: 2012-02-01 16:01:00  mike 2012-02-01 16:00:00 
7: 2012-02-01 16:02:00  mike 2012-02-01 16:00:00 
8: 2012-02-01 16:20:00 steven 2012-02-01 16:00:00 
9: 2012-02-01 17:09:00  mike 2012-02-01 17:00:00 
10: 2012-02-01 18:08:00 steven 2012-02-01 18:00:00 
11: 2012-02-01 18:20:00  mike 2012-02-01 18:00:00 
12: 2012-02-01 19:08:00  mike 2012-02-01 19:00:00