Create an index that increases after each gap in otherwise regularily-increasing row

Question

I\'ve got a samples data frame which contains some readings at regularily-spaced timestamps (1 sec. interval).

                      TS           Pr         


        

Answer 1

 samples$eventID <- cumsum(c(TRUE,diff(as.POSIXct(samples$TS))>1))
 samples
 #                      TS Pressure Temperature eventID
 #8  2014-08-26 00:18:26.8    105.0          30       1
 #9  2014-08-26 00:18:27.8    108.0          32       1
 #10 2014-08-26 00:18:28.8    109.9          31       1
 #11 2014-08-26 00:34:20.8    109.0          20       2
 #12 2014-08-26 00:34:21.8    100.0          24       2
 #13 2014-08-26 00:34:22.8     95.0          22       2