Belle -
Assuming that by=list(mydata$schoolid, mydata$year) was a
typo and should have been by=list(mydata$studentid, mydata$year),
setting
class(day_min$x) = 'POSIXct'
day_min$x = format(day_min$x,'%m/%d/%y %l:%M %p')
should make the mininum days display in the format you want.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Mon, 7 Feb 2011, Belle wrote:
Hi,
I am trying to find the min of day for each student in each year.
Here is the dataset:
date studentid year
1/1/05 6:07 AM 236 20082009
3/27/09 9:45 AM 236 20082009
4/29/09 8:44 AM 236 20082009
3/27/09 11:36 AM 310 20082009
4/1/09 10:43 AM 310 20082009
10/15/09 8:54 AM 310 20092010
10/22/09 8:54 AM 310 20092010
10/28/09 8:06 AM 310 20092010
11/19/09 9:06 AM 310 20092010
10/24/07 9:22 AM 335 20072008
12/13/07 9:26 AM 335 20072008
2/25/09 1:49 PM 335 20082009
3/5/09 2:13 PM 335 20082009
4/15/09 1:53 PM 335 20082009
10/24/07 12:14 PM 126 20072008
11/7/07 12:21 PM 126 20072008
3/19/09 8:45 AM 177 20082009
4/2/09 8:54 AM 177 20082009
4/16/09 9:57 AM 177 20082009
day_min <- aggregate(mydata$date, by=list(mydata$schoolid, mydata$year),
FUN=min)
However, the result shows the date is in format as: "1193242974" instead of
"mm/dd/yy HH:MM AM".
Is there anyway that I can show original date in the result?
Thanks
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