need to delete by time, not date
On May 10, 2011, at 11:06 AM, Schatzi wrote:
I have a matrix where one column has a date and another column has a time. I need to delete all times before 6am. I had combined the Date and Time column into DateTime. Mat1: Weight Date Time 7.6 04/28/11 09:03 8.4 04/29/11 03:11 8.6 04/29/11 05:32 8.6 04/29/11 09:53 1.4 05/01/11 19:52 I tried just picking up the time: as.POSIXct(Mat1$Time, format = "%H:%M") but this assigns the time value today's date.
Since these are either character strings (or factors) at the moment ... and if they are matrices they are character... Mat1[Mat1$Time >= "06:00" , ] If actually a dataframe then Mat1[as.character(Mat1$Time) >= "06:00" , ] In the future please include the output of dput(Mat1).
The final matrix should look like: Weight Date Time 7.6 04/28/11 09:03 8.6 04/29/11 09:53 1.4 05/01/11 19:52
David Winsemius, MD West Hartford, CT