Thanks David, Yes, I am talking about the MASS package.Thank you for pointing out that these scale the same. My question is, how do I get from the V1 data:
V1 1 164.4283 2 166.2492 3 170.5232 4 156.5622 5 127.7540 6 136.7704 7 136.3436 to the other set of data: + 1 -2.3769280 + 2 -2.7049437 + 3 -3.4748309 + 4 -0.9599825 + 5 4.2293774 + 6 2.6052193 + 7 2.6820884 On Mon, Sep 28, 2009 at 3:41 PM, David Winsemius <dwinsem...@comcast.net>wrote: > Your results are the same (after scaling and sign reversal) out to the 4th > decimal place as those from lda (which by the way is almost certainly from > the MASS package and not from an impossible to find "lda package".) > > > read.table(textConnection(txt)) > V1 > 1 164.4283 > 2 166.2492 > 3 170.5232 > 4 156.5622 > 5 127.7540 > 6 136.7704 > 7 136.3436 > > est <-read.table(textConnection(txt)) > > scale(est) > V1 > [1,] 0.7656185 > [2,] 0.8712707 > [3,] 1.1192567 > [4,] 0.3092117 > [5,] -1.3622976 > [6,] -0.8391481 > [7,] -0.8639119 > attr(,"scaled:center") > V1 > 151.233 > attr(,"scaled:scale") > V1 > 17.23484 > > > LD1est <- read.table(textConnection(" LD1 > + 1 -2.3769280 > + 2 -2.7049437 > + 3 -3.4748309 > + 4 -0.9599825 > + 5 4.2293774 > + 6 2.6052193 > + 7 2.6820884"), header=T) > > > > scale(LD1est) > LD1 > 1 -0.7656170 > 2 -0.8712721 > 3 -1.1192555 > 4 -0.3092138 > 5 1.3622976 > 6 0.8391505 > 7 0.8639103 > attr(,"scaled:center") > LD1 > -3.172066e-17 > attr(,"scaled:scale") > LD1 > 3.104591 > > > On Sep 28, 2009, at 5:54 PM, Pete Shepard wrote: > > I am having a problem understanding the lda package. I have a dataset >> here: >> >> [,1] [,2] [,3] >> [1,] 2.95 6.63 0 >> [2,] 2.53 7.79 0 >> [3,] 3.57 5.65 0 >> [4,] 3.16 5.47 0 >> [5,] 2.58 4.46 1 >> [6,] 2.16 6.22 1 >> [7,] 3.27 3.52 1 >> >> If I do the following; >> >> "names(d)<-c("y","x1","x2") >> d$x1 = d$x1 * 100 >> d$x2 = d$x2 * 100 >> g<-lda( y ~ x1 + x2, data=d) >> v2 <- predict(g, d)", >> >> I get; >> LD1 >> 1 -2.3769280 >> 2 -2.7049437 >> 3 -3.4748309 >> 4 -0.9599825 >> 5 4.2293774 >> 6 2.6052193 >> 7 2.6820884 >> >> However, If I do it manually, >> >> "rawdata<-matrix(scan("tab1_1. >> >>> >>> dat"),ncol=3,byrow=T) >>> group <- rawdata[,1] >>> X <- 100 * rawdata[,2:3] >>> Apf <- X[group==1,] >>> Af <- X[group==0,] >>> xbar1 <- apply(Af, 2, mean) >>> S1 <- var(Af) >>> N1 <- dim(Af)[1] >>> xbar2 <- apply(Apf, 2, mean) >>> S2 <- var(Apf) >>> N2 <- dim(Apf)[1] >>> S<-((N1-1)*S1+(N2-1)*S2)/(N1+N2-2) >>> Sinv=solve(S) >>> d<-xbar1-xbar2 >>> b <- Sinv %*% d >>> v <- X %*% b", >>> >>> I get; >>> >>> [,1] >>> [1,] 164.4283 >>> [2,] 166.2492 >>> [3,] 170.5232 >>> [4,] 156.5622 >>> [5,] 127.7540 >>> [6,] 136.7704 >>> [7,] 136.3436 >>> >>> >> >> >> >> >> >> >>> I am having a problem understanding the lda package. I have a dataset >>> here: >>> >>> [,1] [,2] [,3] >>> [1,] 2.95 6.63 0 >>> [2,] 2.53 7.79 0 >>> [3,] 3.57 5.65 0 >>> [4,] 3.16 5.47 0 >>> [5,] 2.58 4.46 1 >>> [6,] 2.16 6.22 1 >>> [7,] 3.27 3.52 1 >>> >>> If I do the following; >>> >>> "names(d)<-c("y","x1","x2") >>> d$x1 = d$x1 * 100 >>> d$x2 = d$x2 * 100 >>> g<-lda( y ~ x1 + x2, data=d) >>> v2 <- predict(g, d)", >>> >>> I get; >>> LD1 >>> 1 -2.3769280 >>> 2 -2.7049437 >>> 3 -3.4748309 >>> 4 -0.9599825 >>> 5 4.2293774 >>> 6 2.6052193 >>> 7 2.6820884 >>> >>> However, If I do it manually, >>> >>> "rawdata<-matrix(scan("tab1_1.dat"),ncol=3,byrow=T) >>> group <- rawdata[,1] >>> X <- 100 * rawdata[,2:3] >>> Apf <- X[group==1,] >>> Af <- X[group==0,] >>> xbar1 <- apply(Af, 2, mean) >>> S1 <- var(Af) >>> N1 <- dim(Af)[1] >>> xbar2 <- apply(Apf, 2, mean) >>> S2 <- var(Apf) >>> N2 <- dim(Apf)[1] >>> S<-((N1-1)*S1+(N2-1)*S2)/(N1+N2-2) >>> Sinv=solve(S) >>> d<-xbar1-xbar2 >>> b <- Sinv %*% d >>> v <- X %*% b", >>> >>> I get; >>> >>> [,1] >>> [1,] 164.4283 >>> [2,] 166.2492 >>> [3,] 170.5232 >>> [4,] 156.5622 >>> [5,] 127.7540 >>> [6,] 136.7704 >>> [7,] 136.3436 >>> >>> >>> It seems there is an extra step that I am missing? The predict step that >>> adds a constant to the second set of values? Can anyone clear this up for >>> me? >>> >> >> > > > David Winsemius, MD > Heritage Laboratories > West Hartford, CT > > [[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.