indicateing to which interval a date belongs

Question

4/1/2014 0:11   40.769  -73.9549    B02512|
4/1/2014 0:17   40.7267 -74.0345    B02512|
4/1/2014 0:21   40.7316 -73.9873    B02512|
4/1/2014 0:28   40.7588 -73.9776    B02512|
4/1/2014 0:33   40.7594 -73.9722    B02512|
4/1/2014 0:33   40.7383 -74.0403    B02512|

and i created a time interval objet that lokks like this C--2014-04-11 00:15:00 UTC 2014-04-11 00:15:00 UTC(part of it ) what i want to do is to to add a column to the raw data, that indicates for each row, for which time interval (which is represented by a single timepoint at the beginning of the time interval) it belongs

so my data would look like this :

4/1/2014 0:11   40.769  -73.9549    B02512  4/1/2014 0:00|
4/1/2014 0:17   40.7267 -74.0345    B02512  4/1/2014 0:15|

how can i do that ?

Answer 1

Using lubridate's floor_date function:

df$interv<-lubridate::floor_date(df$time, unit="15 minutes")

(This assumes that your time column is some recognized date-time format (e.g., POSIXt), which it doesn't seem to be from your sample's formatting.)

For example:

a<-Sys.time()
a
[1] "2019-01-08 09:22:22 EST"
floor_date(a,unit="15 minutes")
[1] "2019-01-08 09:15:00 EST"