dat1<- read.table(text="
Product??? Price??? Year_Month? PE
A??????????????? 100??????? 201012??????? -2
A??????????????? 98????????? 201101??????? -3
A??????????????? 97????????? 201102??????? -2.5
B??????????????? 110??????? 201101??????? -1
B??????????????? 100??????? 201102??????? -2
B????????????????? 90????????? 201103??????? -4
",sep="",header=TRUE,stringsAsFactors=FALSE)
dat1[as.logical(with(dat1,ave(Year_Month,Product,FUN=function(x) x==max(x)))),]
#? Product Price Year_Month?? PE
#3?????? A??? 97???? 201102 -2.5
#6?????? B??? 90???? 201103 -4.0
A.K.
----- Original Message -----
From: Tammy Ma <metal_licaling at live.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Friday, March 15, 2013 5:56 AM
Subject: [R] How to list the all products' information of the latest month?
Hi,
I have data frame like this:
Product? ? Price? ? Year_Month? PE
A? ? ? ? ? ? ? ? 100? ? ? ? 201012? ? ? ? -2
A? ? ? ? ? ? ? ? 98? ? ? ? ? 201101? ? ? ? -3
A? ? ? ? ? ? ? ? 97? ? ? ? ? 201102? ? ? ? -2.5
B? ? ? ? ? ? ? ? 110? ? ? ? 201101? ? ? ? -1
B? ? ? ? ? ? ? ? 100? ? ? ? 201102? ? ? ? -2
B? ? ? ? ? ? ? ? ? 90? ? ? ? ? 201103? ? ? ? -4
How can I achieve the following result using R:
Product? ? Price? ? Year_Month? PE
A? ? ? ? ? ? ? ? 97? ? ? ? ? 201102? ? ? ? -2.5
B? ? ? ? ? ? ? ? ? 90? ? ? ? ? 201103? ? ? ? -4
in other words, list the all products' information of the latest month?
Thanks for your help.
Kind regards,
Lingyi
??? ??? ??? ? ??? ??? ?
??? [[alternative HTML version deleted]]
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