[julia-users] Getting sequence of time and subset it

[akrun]

I have a dataset similar to the one below

   sdt1 = DataFrame(ID = 1:2, StartTime = DateTime(["4/13/2016 07:00", 
"4/13/2016 07:15"], "m/d/y H:M"), 
                            EndTime = DateTime(["4/13/2016 12:00", 
"4/13/2016 12:15"], "m/d/y H:M"),
                            BreakTime1 = DateTime(["4/13/2016 10:00", 
"4/13/2016 10:15"], "m/d/y H:M"),
                            BreakTime2 = DateTime(["4/13/2016 12:00", 
"4/13/2016 12:15"], "m/d/y H:M") 
                            )

I can get the sequence of date time using

   for i in 1:nrow(sdt1)
   si = 
Dates.format([sdt1[i,:StartTime]:Dates.Minute(30):sdt1[i,:EndTime]], 
"HH:MM")
    println(si)
  end 

#Any["07:00","07:30","08:00","08:30","09:00","09:30","10:00","10:30","11:00","11:30","12:00"]
#Any["07:15","07:45","08:15","08:45","09:15","09:45","10:15","10:45","11:15","11:45","12:15"]


Suppose I want to subset the sequence to not include the times in BreakTime 
columns, how do I do it?  I have tried
  for i in 1:nrow(sdt1)
    si = 
Dates.format([sdt1[i,:StartTime]:Dates.Minute(30):sdt1[i,:EndTime]], 
"HH:MM")
     println(si in sdt1[i, [:BreakTime1, :BreakTime2]])
   end                     

I get an error message
MethodError: `start` has no method matching start(::DataFrames.DataFrame)
 in mapreduce_sc_impl at reduce.jl:194
 in in at reduce.jl:377
 
I can do this using data.table in R

    library(data.table)
    dt1 <- data.table(ID = 1:2, StartTime =as.POSIXct(c("4/13/2016 07:00", 
"4/13/2016 07:15"), "%m/%d/%Y %H:%M", tz = "GMT"), 
                            EndTime =as.POSIXct(c("4/13/2016 14:00", 
"4/13/2016 14:15"), "%m/%d/%Y %H:%M", tz = "GMT"),
                            BreakTime1 = as.POSIXct(c("4/13/2016 10:00", 
"4/13/2016 10:15"), "%m/%d/%Y %H:%M", tz = "GMT"),
                            BreakTime2 = as.POSIXct(c("4/13/2016 12:00", 
"4/13/2016 12:15"), "%m/%d/%Y %H:%M", tz = "GMT"))
    dt1[, {
     s1 <- head(seq(StartTime, EndTime, by = "30 min"), -1)
     list(time= format(s1[!s1 %in% c(BreakTime1, BreakTime2)], "%H:%M"))}, 
      by = ID]
    ID  time
 1:  1 07:00
 2:  1 07:30
 3:  1 08:00
 4:  1 08:30
 5:  1 09:00
 6:  1 09:30
 7:  1 10:30
 8:  1 11:00
 9:  1 11:30
10:  1 12:30
11:  1 13:00
12:  1 13:30
13:  2 07:15
14:  2 07:45
15:  2 08:15
16:  2 08:45
17:  2 09:15
18:  2 09:45
19:  2 10:45
20:  2 11:15
21:  2 11:45
22:  2 12:45
23:  2 13:15
24:  2 13:45

Thanks.