[R] need to delete by time, not date

[Adele_Thompson at cargill.com]

Thanks, that did exactly what I wanted. I realize that I didn't put it in the best form, but was having trouble coming up with a replicable example. I see that many people here quickly create examples and I am learning how to do that, but still struggle, especially when using as.POSIXct and other more complex classes.
Thanks for the help.

-----Original Message-----
From: dwinsemius at comcast.net [mailto:dwinsemius at comcast.net] 
Sent: Tuesday, May 10, 2011 10:19 AM
To: Thompson, Adele - Adele_Thompson at cargill.com
Cc: r-help at r-project.org
Subject: Re: [R] 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