On Fri, 2009-09-11 at 13:10 -0700, Noah Silverman wrote: > Hi, > > Is there an alternative to the scale function where I can specify my own > mean and standard deviation?
A couple of calls to sweep? See ?sweep set.seed(123) dat <- data.frame(matrix(runif(10*10), ncol = 10)) xbar <- colMeans(dat) sigma <- apply(dat, 2, sd) dat.std <- sweep(sweep(dat, 2, xbar, "-"), 2, sigma, "/") ## compare scale(dat) HTH > > I've come across an interesting issue where this would help. > > I'm training and testing on completely different sets of data. The > testing set is smaller than the training set. > > Using the standard scale function of R seems to introduce some error. > Since it scales data WITHIN the set, it may scale the same number to > different value since the range in the training and testing set may be > different. > > My thought was to scale the larger training set of data, then use the > mean and SD of the training data to scale the testing data according to > the same parameters. That way a number will transform to the same > result regardless of whether it is in the training or testing set. > > I can't be the first one to have looked at this. Does anyone know of a > function in R or if there is a scale alternative where I can control the > parameters? > > Thanks! > > -- > Noah > > ______________________________________________ > 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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ 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.