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$zGPA<-rowWeightedMeans(as.matrix(Master[,-1]),Units) Master # SID B2A B2B B2C C2A C2B C2C C118A C118B C118C zGPA #1 1 0.01 0.50 -0.4 1.2 -1.8 0.3 -0.3 0.4 0.5 0.035121951 #2 2 0.01 0.50 -0.4 0.5 -0.4 1.2 -1.8 0.3 -0.3 -0.003902439 #3 3 0.04 0.05 0.5 -0.4 -0.5 0.4 -1.2 1.8 0.3 0.097804878 A.K. ----- Original Message ----- From: Robert Lynch <robert.b.ly...@gmail.com> To: r-help@r-project.org Cc: Sent: Monday, July 22, 2013 6:12 PM Subject: [R] weighted average I am trying to compute GPA from class grades(which have been normallized) I have for example the following matrix Master = SID B2A B2B B2C C2A C2B C2C C118A C118B C118C 001 0.01 0.5 -0.4 1.2 -1.8 0.3 -0.3 0.4 0.5 002 0.01 0.5 -0.4 0.5 -0.4 1.2 -1.8 0.3 -0.3 003 0.04 0.05 0.5 -0.4 - 0.5 0.4 -1.2 1.8 0.3 etc Where each column has a zero mean and a standard deviation of 1. I want to calculate a weighted average for each row(student ID) that takes into account that B2A, C118A, C118B, and C118C are all 4 unit classes, and the rest, B2B, B2C, C2A,C2B,C2C are 5 unit classes I have tried Units<-c(4,5,5,5,5,5,4,4,4) Master$zGPA <-weighted.means(Master[,2:10],Units) But that gets me one number and not a vector. [[alternative HTML version deleted]] ______________________________________________ R-help@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. ______________________________________________ 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.
