Tena koe John
One way:
johnData <- data.frame(id=rep(LETTERS[1:5],20), distance=rnorm(1:100, mean =
100), bearing=sample(1:360,100,replace=T), month=sample(1:12,100,replace=T))
johnAgg <- aggregate(johnData[,'distance'], johnData[,c('id','month')], max)
names(johnAgg)[3] <- 'distance'
merge(johnAgg, johnData)
HTH ....
Peter Alspach
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of rjb
Sent: Friday, 24 August 2012 9:19 a.m.
To: r-help@r-project.org
Subject: [R] Extracting data from dataframe with tied rows
Hi R help,
I'm a fairly experienced R user but this manipulation has me stumped, please
help:
DATA
id<-rep(LETTERS[1:5],20)
distance<-rnorm(1:100, mean = 100)
bearing<-sample(1:360,100,replace=T)
month<-sample(1:12,100,replace=T)
I have a dataset with records of individuals (id) , each with a distance
(distance) & direction (bearing) recorded for each month (month).
I want to find the largest distance per individual per month, which is easy
with /tapply/ or /melt/cast (reshape)/,
head(DATA_m<-melt(DATA,id=c("id","month")))
cast(DATA_m,id+month~.,max)
OR
na.omit(melt(tapply(distance,list(id,month),max)))
*BUT THE CATCH IS* ,
I also want the the *corresponding* bearing for that maximum distance per
month. I've tried the steps above plus using which.max() and loops, but
can't solve the problem. The real dataset is about 6000 rows.
I'm guessing the answer is in finding the row number from the original DATA
but I can't figure how to do that with tapply or melt.
Any suggestions would be greatly appreciated.
John Burnside
--
View this message in context:
http://r.789695.n4.nabble.com/Extracting-data-from-dataframe-with-tied-rows-tp4641140.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
The contents of this e-mail are confidential and may be subject to legal
privilege.
If you are not the intended recipient you must not use, disseminate,
distribute or
reproduce all or any part of this e-mail or attachments. If you have received
this
e-mail in error, please notify the sender and delete all material pertaining
to this
e-mail. Any opinion or views expressed in this e-mail are those of the
individual
sender and may not represent those of The New Zealand Institute for Plant and
Food Research Limited.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
