try this:
> x <- structure(list(speed = c(3,9,14,8,7,6), result = c(0.697, 0.011, 0.015,
> 0.012, 0.018, 0.019), house = c(1,
+ 1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
+ id = c("1000", "10000",
+ "10001", "10002", "10003", "10004")), .Names = c("speed",
+ "result", "house", "date", "id"), class = "data.frame", row.names = c("1000",
+ "10000", "10001", "10002", "10003", "10004"))
>
> require(plyr)
> ddply(x, .(date), .fun = function(a){
+ a[which.min(a$speed), ]
+ })
speed result house date id
1 3 0.697 1 719 1000
2 8 0.012 1 1027 10002
3 6 0.019 1 1030 10004
>
>
On Mon, Jan 9, 2012 at 8:23 PM, Jeffrey Joh <johjeff...@hotmail.com> wrote:
>
>
>
>
> For each date, I would like to keep the line with the lowest speed and
> discard the rest. The result would have one line for each date. Can I use
> aggregate for this?
>
> My table is as follows:
> structure(list(speed = c(3,9,14,8,7,6), result = c(0.697, 0.011, 0.015,
> 0.012, 0.018, 0.019), house = c(1,
> 1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
> id = c("1000", "10000",
> "10001", "10002", "10003", "10004")), .Names = c("speed",
> "result", "house", "date", "id"), class = "data.frame", row.names = c("1000",
> "10000", "10001", "10002", "10003", "10004"))
>
> Thanks,
> Jeffrey
>
>
> [[alternative HTML version deleted]]
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
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