Displaying 2 results from an estimated 2 matches for "max_date".
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max_data
2013 May 23
3
Removing rows w/ smaller value from data frame
Hello,
I have a column called max_date in my data frame and I only want to keep the
bigger values for the same activity. How can I do that?
data frame:
activity max_dt
A 2013-03-05
B 2013-03-28
A 2013-03-28
C 2013-03-28
B 2013-03-01
Thank you for your help
--
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2010 Feb 09
1
Aggregate dataframe variables, return more than 2 vars
...id x.decod.1. end
1 1 COMPLETE 2005-08-29
2 2 COMPLETE 2005-08-29
3 3 WITHDRAWAL 2005-08-29
I can get the max date and the id 2 different ways:
> do.call("rbind", lapply(split(dat, dat$id), function(x) data.frame(id =
x$id[1], max_date = max(x$date))))
id end
1 1 2005-08-29
2 2 2005-08-29
3 3 2005-08-29
OR
> aggregate(dat$date, list(USUBJID=dat$id),FUN="max")
USUBJID x
1 1 13024
2 2 13024
3 3 13024
(which oddly returns some number of days after 1-1-1970 iso of the max as...