How to group Time Series data into round intervals of 5 minutes in R?

I have a time series data frame looking like this:

  Time                 Source  Value
1 2016-01-20 15:10:04  C04     OPEN
2 2016-01-20 15:09:57  M04     true
3 2016-01-20 15:09:53  M02     true
4 2016-01-20 15:09:53  M03     true
5 2016-01-20 14:44:54  M04     true

now I would like to group them in intervals of 5 minutes starting from 00:00:00, so that I get intervals of 0-5-10-15-20... and so on. The intervals shall be used later as a group identifier:

  Time                 Source  Value  Group
1 2016-01-20 15:10:04  C04     OPEN   10
2 2016-01-20 15:09:57  M04     true   5
3 2016-01-20 15:09:53  M02     true   5
4 2016-01-20 15:09:53  M03     true   5
5 2016-01-20 14:44:54  M04     true   40

I already tried to cut() the dates using breaks="5 min" but instead of getting round start and end values, the result looks like this:

 > table(cut.POSIXt(df.formatted$Time, breaks="5 min"))[1:5]
 2015-12-31 12:49:00 2015-12-31 12:54:00 2015-12-31 12:59:00 2015-12-31 13:04:00 2015-12-31 13:09:00 
              4                   0                   0                   1                  15

Is there a way to tell cut() to use round time intervals? I also tried the grouping using xts package, but got more confused by the OHLC than it helped me. Also I tried using the heR.Misc package (see time.factor documentation but due to the poor documentation I couldn't get it to run properly.

Does someone maybe know how to solve this problem?

Solution

First, you need to install "chron" package. This package has minutes() function that gives you the minute of your time.

I have to paste first and second column together but i don't think you have to do too. Use just tmpTime <- tmp[,1]

library(chron)

tmp <- read.table(text="Time  Source  Value
 2016-01-20 15:10:04  C04     OPEN
 2016-01-20 15:09:57  M04     true
 2016-01-20 15:09:53  M02     true
 2016-01-20 15:09:53  M03     true
 2016-01-20 14:44:54  M04     true", header=T, row.names= NULL)

tmpTime <- paste(tmp[,1], tmp[,2])

group <- seq(0,55,5)

sapply(tmpTime, function(x){
  x <- minutes(x)
  for(i in 2:length(group)){
    if(x < group[i]) {return(group[i-1]); break}
    else if(x >= group[length(group)]) return(group[length(group)])
  }
})

[1] 10  5  5  5 40