predict.qda
From MASS v7.3-0
by Brian Ripley
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$prior,
method = c("plug-in", "predictive", "debiased", "looCV"), ...)
Arguments
- object
- object of class
"qda"
- newdata
- data frame of cases to be classified or, if
object
has a formula, a data frame with columns of the same names as the variables used. A vector will be interpreted as a row vector. If newdata is missing, an attempt will be made to ret - prior
- The prior probabilities of the classes, by default the proportions in the
training set or what was set in the call to
qda
. - method
- This determines how the parameter estimation is handled. With
"plug-in"
(the default) the usual unbiased parameter estimates are used and assumed to be correct. With"debiased"
an unbiased estimator of the log posterior probabili - ...
- arguments based from or to other methods
Details
This function is a method for the generic function
predict()
for class "qda"
.
It can be invoked by calling predict(x)
for an
object x
of the appropriate class, or directly by
calling predict.qda(x)
regardless of the
class of the object.
Missing values in newdata
are handled by returning NA
if the
quadratic discriminants cannot be evaluated. If newdata
is omitted and
the na.action
of the fit omitted cases, these will be omitted on the
prediction.
Value
- a list with components
class The MAP classification (a factor) posterior posterior probabilities for the classes
References
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.
Ripley, B. D. (1996) Pattern Recognition and Neural Networks. Cambridge University Press.
See Also
Examples
tr <- sample(1:50, 25)
train <- rbind(iris3[tr,,1], iris3[tr,,2], iris3[tr,,3])
test <- rbind(iris3[-tr,,1], iris3[-tr,,2], iris3[-tr,,3])
cl <- factor(c(rep("s",25), rep("c",25), rep("v",25)))
zq <- qda(train, cl)
predict(zq, test)$class
Community examples
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