Message-ID: <6AA4113F-3050-4903-B2BB-2618367A59F3@comcast.net>
Date: 2011-05-10T15:18:31Z
From: David Winsemius
Subject: need to delete by time, not date
In-Reply-To: <1305039982537-3512162.post@n4.nabble.com>
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