>From your email, it seems like aggregate() is working.
Could you please provide the sessionInfo()?
My guess is that some other loaded library is masking the summarize().
For example, if I load
library(Hmisc)
#The following object is masked from ?package:plyr?:
#
?# ? is.discrete, summarize
ddply(datNew,.(activity),summarize, max_dt=max(max_dt)) #
#Error in is.list(by) : 'by' is missing
?ddply(datNew,.(activity),plyr::summarize,max_dt=max(max_dt))
#? activity???? max_dt
#1??????? A 2013-03-28
#2??????? B 2013-03-28
#3??????? C 2013-03-28
A.K.
----- Original Message -----
From: "Mossadegh, Ramine N." <Ramine.Mossadegh at finra.org>
To: arun <smartpink111 at yahoo.com>
Cc:
Sent: Thursday, May 23, 2013 10:44 AM
Subject: RE: [R] Removing rows w/ smaller value from data frame
Thank but I get : Error in is.list(by) : 'by' is missing
When I tried ddply(datNew,.(activity),summarize, max_dt=max(max_dt))
-----Original Message-----
From: arun [mailto:smartpink111 at yahoo.com]
Sent: Thursday, May 23, 2013 10:40 AM
To: Mossadegh, Ramine N.
Cc: R help
Subject: Re: [R] Removing rows w/ smaller value from data frame
Hi,
Try:
datNew<- read.table(text="
activity??? max_dt
A??????????? 2013-03-05
B??????????? 2013-03-28
A??????????? 2013-03-28
C??????????? 2013-03-28
B??????????? 2013-03-01
",sep="",header=TRUE,stringsAsFactors=FALSE)
datNew$max_dt<- as.Date(datNew$max_dt)
?aggregate(max_dt~activity,data=datNew,max)
#? activity???? max_dt
#1??????? A 2013-03-28
#2??????? B 2013-03-28
#3??????? C 2013-03-28
#or
library(plyr)
?ddply(datNew,.(activity),summarize, max_dt=max(max_dt)) #? activity???? max_dt
#1??????? A 2013-03-28
#2??????? B 2013-03-28
#3??????? C 2013-03-28
#or
ddply(datNew,.(activity),summarize, max_dt=tail(sort(max_dt),1)) #? activity????
max_dt
#1??????? A 2013-03-28
#2??????? B 2013-03-28
#3??????? C 2013-03-28
A.K.
----- Original Message -----
From: ramoss <ramine.mossadegh at finra.org>
To: r-help at r-project.org
Cc:
Sent: Thursday, May 23, 2013 10:23 AM
Subject: [R] 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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