R: Calculate measurement time-points for separate samples
问题 I have measured concentrations of N2O for different samples (Series) during 10 min intervals. Each sample was measured two times a day for 9 days. The N2O analyzer saved data (conc.) every second! My data now looks like this: DATE Series V A TIME Concentration 1: 2017-10-18T00:00:00Z O11 0.004022 0.02011 10:16:00.746 0.3512232 2: 2017-10-18T00:00:00Z O11 0.004022 0.02011 10:16:01.382 0.3498687 3: 2017-10-18T00:00:00Z O11 0.004022 0.02011 10:16:02.124 0.3482681 4: 2017-10-18T00:00:00Z O11 0