similar to: Quadratic Discriminant Analysis (qda)

Dear R Help Members, I am aware how to plot the LD1 vs LD2 from a lda in R, using the code: plot(baseline.systat.hat$x, col=baseline.systat.hat$class,pch=as.numeric(baseline.systat.hat$class)) However, I need to use the quadratic discriminant function, qda due to data properties. Is there a way to obtain the same sort of plot for from a qda object (and the output of predict qda). I have not

Hi, I'm a R newbie and I have a supervised 2-class classification problem. To find out the best representation of my data (dim = 45). I want to perform LDA und QDA on the diffrent data representations to find out, which is best to discriminate the 2 sets. For LDA there exists a method plot.lda shows (in the 2 class case) a histogramm of the data, projected onto the linear discriminants (pleas

Dear R user, I'm using qda (quadratic discriminant analysis) function (package MASS) to classify 58 explanatory variables (numeric type with different ranges) using a grouping variable (factor 2 levels "0" "1"). I'm using the qda method for class 'data.frame' (in this way I don't need to specify a formula). Using the function:

Can one perform a QDA in R? I do not see it anywhere within the mda package. Any pointers here would be appreciated. Thanks, cjf -- ~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~* Christopher J. Fonnesbeck Ph.D. Student Georgia Cooperative Wildlife Unit University of Georgia Athens, GA 30602 Email: cjf at fonnesbeck.net Yahoo: fonnesbeck_chris ~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

Perhaps, I should complement my previous e-mail question: I am trying to select variables through a quadratic discriminant analysis. It seems to me that a robust criterion is the value of the discriminatory power (i.e. the ratio of the separation of the class means to within-class variance) How can I obtain this ratio from V & R's qda() output ? Thanks (I hope this question is relevant) --

Hi, I have been using some of the functions in r for classification purposes, chiefly lda, qda, knn and nnet. My problem is that the only one I can figure out how to represenent graphically is lda (using plot.lda). I have tried 'fooling' this function into accepting qda input for plotting but to no avail. I wonder if you have any suggestions? Thanks alot, Anne Marie Power Marine lab.

Hi, I am not sure if I remember correctly a mail last week to this messageboard where Prof Ripley said Fisher's discriminants are not used in lda within R and that Rao's are used instead, is this true? I looked in MASS (1996) but I couldn't find the reference to this in chapter 12 (multivariate analysis), the (help)lda doesn't tell me either. Could anyone tell me where can I

Hi, What does this mean when I have something like: > qda.boot <- boot(train, qda.bootstrap, R = 500) Error in qda.default(structure(data.matrix(x), class = "matrix"), ...) : Rank deficiency in group M with my qda.bootstrap() looks something like: > qda.bootstrap <- function(data, index) { + boot.qda <- qda(x = data[index, 2:9], group = data[index, 1]) + qda.pred

z <- qda(train, cl) save(z, file = "qda.dat") load("qda.dat") predict(qda.dat, test)$class I'm trying to save z where z <-qda(train, cl) and load z for later use in predict(z, test)$class. I think I successfully saved z by save(z, file = "qda.dat") but when I tried to load by load("qda.dat") and call predict(qda.dat, test)$class, it gives me error

Hi, I'm a newbie in R and don't much aobut all the modules and their capabilities, but I'm interested in solving a problem about a discriminant analysis done with SPSS tool. The thing is that I would like to make a discrimant analysis similar to the one done with SPSS, but I can't find the way to solve it. I've been playing with R and I can handle more or less my data,

You need to learn how to access code for nonexported methods. See ? "::" > methods(qda) [1] qda.data.frame* qda.default* qda.formula* qda.matrix* see '?methods' for accessing help and source code Shows you that the methods are not exported from the namespace. Hence you need to use the triple colon operator to see their code: > MASS:::qda Once you have the code, I

I guess the question that is being asked here is what is the scaling matrix that is being returned in the qda object. The help file on qda() says: ... scaling: for each group ?i?, ?scaling[,,i]? is an array which transforms observations so that within-groups covariance matrix is spherical. ... This is a bit ambiguous. I tried a few cases (spectral, QR decomposition, especially given that it is an

Hi, the following strange error appears when I use qda: > qda1 <- qda(as.data.frame(mfilters[cvtrain,]),as.factor(traingroups)) Error: function is not a closure That's also strange: > qda1 <- qda(mfilters[cvtrain,],as.factor(traingroups)) Error in qda.default(mfilters[cvtrain, ], as.factor(traingroups)) : length of dimnames must match that of dims Some backgroud: >

Dear list, (I've not upgraded to R1.4 yet) I have the following $class component in a predict.qda object: > unique(mod23S.qda.pred$class) [1] 12 17 8 10 4 9 5 13 14 19 20 15 6 3 7 1 23 11 18 21 16 2 22 NA Levels: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Nevertheless, when I try to identify the individual(s) with NA, I get: >

can you run weft qda on mac with virtual PC? (this is how nvivo and some others work for the mac). us poor mac users...but i commend the open source effort! best, Lisa Lisa Schwartz Language Reading and Culture University of Arizona ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile.

Hello, I am Souradeep Chattopadhyay and I am a graduate student at Iowa State University Department of Statistics. Can anyone please explain the mathematical formulation behind the scaling matrix returned by the qda function in MASS package. I want to understand how this scaling matrix is derived from the inputs given to the qda function. Example Code The following example is using

Dear wxruby users I''ve been trying to get wxruby-based weft-qda 0.9.6 running on a linux from scratch 6.1 system (this list had a discussion about weft-qda last year and alex fenton''s also been trying to help me out - no luck so far). I get stuck with wxruby 0.60 (I think). I compiled wxruby against wxGTK 2.4.2 (without gtk2, without unicode - gtk+ version is 1.2.10) - after

Hello, Does logistic regression really provide better results than lda or qda ? (my purpose is not classification but highlighting of discriminant variables). If this is true, where could I get an R script performing stepwise logistic regression ? Thanks -- Daniel AMORESE Lab. M2C "Morphodynamique Continentale et C?ti?re" UMR CNRS 6143 Caen/Rouen Centre de G?omorphologie UCBN

Hi Weft QDA 1.0.1''s available now. It''s a bug-fix and maintenance release, and a recommended upgrade for existing users. What''s new: - fix for crash when moving categories using the Category Tree - fixed a bug on Win 98 and Win ME that made Weft a ''non-starter'' - avoid crashes with over-large and malformed text documents - fix a text scrolling bug on

Hi all, If I run LDA on the same data (2-class classification) with default(no priors specified in the lda function) vs. "prior=c(0.5, 0.5)", the results are different. The (0.5, 0.5) priors give better 1-classify-to-1 rate, and the proportional priors(default, no priors specified in the lda function) give better 0-classify-to-0 rate, for both training and testing data sets. However,