predict.qda

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Classify from Quadratic Discriminant Analysis

Classify multivariate observations in conjunction with qda

Keywords
multivariate
Usage
## S3 method for class 'qda':
predict(object, newdata, prior = object$prior,
        method = c("plug-in", "predictive", "debiased", "looCV"), ...)
Arguments
object
object of class "qda"
newdata
data frame of cases to be classified or, if object has a formula, a data frame with columns of the same names as the variables used. A vector will be interpreted as a row vector. If newdata is missing, an attempt will be made to ret
prior
The prior probabilities of the classes, by default the proportions in the training set or what was set in the call to qda.
method
This determines how the parameter estimation is handled. With "plug-in" (the default) the usual unbiased parameter estimates are used and assumed to be correct. With "debiased" an unbiased estimator of the log posterior probabili
...
arguments based from or to other methods
Details

This function is a method for the generic function predict() for class "qda". It can be invoked by calling predict(x) for an object x of the appropriate class, or directly by calling predict.qda(x) regardless of the class of the object.

Missing values in newdata are handled by returning NA if the quadratic discriminants cannot be evaluated. If newdata is omitted and the na.action of the fit omitted cases, these will be omitted on the prediction.

Value

  • a list with components
  • classThe MAP classification (a factor)
  • posteriorposterior probabilities for the classes

References

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.

Ripley, B. D. (1996) Pattern Recognition and Neural Networks. Cambridge University Press.

See Also

qda, lda, predict.lda

Aliases
  • predict.qda
Examples
tr <- sample(1:50, 25)
train <- rbind(iris3[tr,,1], iris3[tr,,2], iris3[tr,,3])
test <- rbind(iris3[-tr,,1], iris3[-tr,,2], iris3[-tr,,3])
cl <- factor(c(rep("s",25), rep("c",25), rep("v",25)))
zq <- qda(train, cl)
predict(zq, test)$class
Documentation reproduced from package MASS, version 7.3-38, License: GPL-2 | GPL-3

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