[R] qda(MASS) function error
Mauro Rossi
Mauro.Rossi at irpi.cnr.it
Wed Jul 25 18:17:49 CEST 2007
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:
result.qda<-qda(explanatory.variables, grouping.variable, method="moment")
I obtain the following error message:
"Error in qda.default(x, grouping, ...) : rank deficiency in group 0"
I run the script excluding some variables and I've individuated 2
explanatory variables that give problems, but I don't understand why
they give them. The two excluded variables are numeric with two possible
values: 0 and 1, but in the rest of group of variables, some similar
variables are considered.
I don't have this problem using lda function for linear discriminant
analysis.
What does this error message mean?
What types of variables does qda function consider?
Thank in advance,
Mauro Rossi
--
Mauro Rossi
Istituto di Ricerca per la Protezione Idrogeologica
Consiglio Nazionale delle Ricerche
Via della Madonna Alta, 126
06128 Perugia
Italia
Tel. +39 075 5014421
Fax +39 075 5014420
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