performing function on data frame
As Michael notes, scale is what you want. Also, your request has an incorrect definition of z scores: d$y - mean(d$y)/sd(d$y) #incorrect (d$y - mean(d$y) ) / sd(d$y) #correct On Thu, Apr 16, 2009 at 7:40 AM, Michael Conklin
<michael.conklin at markettools.com> wrote:
newDF<-as.data.frame(scale(oldDF)) see ?scale Hope that helps. Michael Conklin -----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Karin Lagesen Sent: Thursday, April 16, 2009 5:29 AM To: r-help at r-project.org Subject: Re: [R] performing function on data frame David Hajage <dhajage.r at gmail.com> writes:
Hi Karin, I'm not sure I understand... Is this what you want ? d$y - mean(d$y)/sd(d$y)
Yes, and also a bit no. Each column in my data frame represents one data set. For every element in this data set I want to know the z value for that element. I.e: I want to create a new data frame from the old data frame, where each element in the new data frame is newDF[i,j] = oldDF[i,j] - mean(d[,j]) / sddev(d[,j]) I could, I think, iterate like this over the data frame, but I keep thinking that one of the apply functions should be employed... Karin -- Karin Lagesen, Ph.D. karin.lagesen at medisin.uio.no http://folk.uio.no/karinlag
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