On Jul 22, 2013, at 3:12 PM, Robert Lynch wrote: > 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$zGPA <-weighted.means(Master[,2:10],Units) > > But that gets me one number and not a vector.
Perhaps something along lines of Master$zGPA <-sapply( weighted.means(Master[,2:10], weighted.means, weghts=Units) (Untested in absence of data or name of package from which function is loaded.) > ?weighted.means No documentation for ‘weighted.means’ in specified packages and libraries: you could try ‘??weighted.means’ --- David Winsemius Alameda, CA, USA ______________________________________________ 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.