Thanks all for the help!
-Original Message-
From: William Dunlap [mailto:wdun...@tibco.com]
Sent: Tuesday, March 09, 2010 5:58 PM
To: Phil Spector; Tan, Richard
Cc: r-help@r-project.org
Subject: RE: [R] data frame select max group by like function
And yet another way is
> isLastIn
To: Tan, Richard
> Cc: r-help@r-project.org
> Subject: Re: [R] data frame select max group by like function
>
> Yet another way to do this with base R:
>
> > dat = read.csv(textConnection('ID, year, score
> + tom, 1995, 88
> + rick, 1994, 90
> + mary, 2000
Try this. The aggregate call gives a data frame with the ID and max
score. Then we merge that back with the original data frame so that
we pick up the year too:
merge(DF, aggregate(DF['score'], DF['ID'], max))
On Tue, Mar 9, 2010 at 1:35 PM, Tan, Richard wrote:
> Hi, I have a data frame with 3
Yet another way to do this with base R:
dat = read.csv(textConnection('ID, year, score
+ tom, 1995, 88
+ rick, 1994, 90
+ mary, 2000, 97
+ tom, 1998, 60
+ mary, 1998,100'))
do.call(rbind,lapply(split(dat,dat$ID),function(x)x[which.max(x$score),]))
ID year score
mary mary 1998 100
ric
s.
Bert Gunter
Genentech Nonclinical Biostatistics
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Ista Zahn
Sent: Tuesday, March 09, 2010 11:00 AM
To: Tan, Richard
Cc: r-help@r-project.org
Subject: Re: [R] data frame select ma
I find ddply() in package plyr handy for this sort of thing:
library(plyr)
f <- function(x) x[which.max( x[["score"]] ), ]
## x will be a subset of Dat according to ID
ddply(Dat, "ID", f)
-Peter Ehlers
On 2010-03-09 11:59, Ista Zahn wrote:
Hi Richard,
There are probably better ways, bu
Hi Richard,
There are probably better ways, but here is one approach:
Dat <- read.table(textConnection("ID, year, score
tom, 1995, 88
rick, 1994, 90
mary, 2000, 97
tom, 1998, 60
mary, 1998,100"), header=TRUE, sep=",")
MaxScore <- aggregate(Dat$score, list(Dat$ID), max)
names(MaxScore) <- c("ID",
Try this:
library(sqldf)
sqldf("SELECT ID, Year, MAX(score) FROM DF GROUP BY ID")
Or
do.call(rbind, lapply(split(DF <- DF[order(DF$score),], DF$ID), tail, 1))
On Tue, Mar 9, 2010 at 3:35 PM, Tan, Richard wrote:
> Hi, I have a data frame with 3 columns: ID, year and score. How can I
> select f
Hi, I have a data frame with 3 columns: ID, year and score. How can I
select for each unique ID, the year that has the max score? For
example, for data frame
ID, year, score
tom, 1995, 88
rick, 1994, 90
mary, 2000, 97
tom, 1998, 60
mary, 1998,100
I shall have
ID, year, score
tom, 1995, 88
ric
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