Message-ID: <1374531995.72771.YahooMailNeo@web142602.mail.bf1.yahoo.com>
Date: 2013-07-22T22:26:35Z
From: arun
Subject: weighted average
In-Reply-To: <CACYeG1joTMSq8ntOaac-e6RtGf6Cv-4cf1dpkgr6DVDvAdkmHA@mail.gmail.com>
Hi,
May be this helps:
Master<-read.table(text="
SID??? B2A??? B2B??? B2C? C2A??? C2B??? C2C??? C118A??? C118B???? C118C
001??? 0.01??? 0.5????? -0.4??? 1.2????? -1.8??? 0.3????? -0.3????? 0.4?? 0.5
002??? 0.01??? 0.5????? -0.4??? 0.5????? -0.4??? 1.2????? -1.8????? 0.3? -0.3
003??? 0.04??? 0.05??? 0.5??? -0.4??? -0.5??? 0.4????? -1.2????? 1.8???? 0.3
",sep="",header=TRUE)
?library(matrixStats)
? Master$zGPA<-rowWeightedMeans(as.matrix(Master[,-1]),Units)
?Master
#? SID? B2A? B2B? B2C? C2A? C2B C2C C118A C118B C118C???????? zGPA
#1?? 1 0.01 0.50 -0.4? 1.2 -1.8 0.3? -0.3?? 0.4?? 0.5? 0.035121951
#2?? 2 0.01 0.50 -0.4? 0.5 -0.4 1.2? -1.8?? 0.3? -0.3 -0.003902439
#3?? 3 0.04 0.05? 0.5 -0.4 -0.5 0.4? -1.2?? 1.8?? 0.3? 0.097804878
A.K.
----- Original Message -----
From: Robert Lynch <robert.b.lynch at gmail.com>
To: r-help at r-project.org
Cc:
Sent: Monday, July 22, 2013 6:12 PM
Subject: [R] weighted average
I am trying to compute GPA from class grades(which have been normallized)
I have for example the following matrix
Master =
SID? ? B2A? ? B2B? ? B2C? C2A? ? C2B? ? C2C? ? C118A? ? C118B? ? C118C
001? ? 0.01? ? 0.5? ? ? -0.4? ? 1.2? ? ? -1.8? ? 0.3? ? ? -0.3? ? ? 0.4
? ? ? ? ? 0.5
002? ? 0.01? ? 0.5? ? ? -0.4? ? 0.5? ? ? -0.4? ? 1.2? ? ? -1.8? ? ? 0.3
? ? ? ? ? -0.3
003? ? 0.04? ? 0.05? ? 0.5? ? -0.4? ? - 0.5? ? 0.4? ? ? -1.2? ? ? 1.8
? ? ? ? 0.3
etc
Where each column has a zero mean and a standard deviation of 1.? I want to
calculate a weighted average for each row(student ID) that takes into
account that
B2A, C118A, C118B, and C118C are all 4 unit classes, and the rest, B2B,
B2C, C2A,C2B,C2C are 5 unit classes
I have tried
Units<-c(4,5,5,5,5,5,4,4,4)
Master$zGPA <-weighted.means(Master[,2:10],Units)
But that gets me one number and not a vector.
??? [[alternative HTML version deleted]]
______________________________________________
R-help at 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.