amdai: Adaptive Mixture Discriminant Analysis (inductive approach)

Description Usage Arguments Value Author(s) References Examples

View source: R/amdai.R

Description

The adaptive mixture discriminant analysis (AMDA) allows to adapt a model-based classifier to the situation a class represented in the test set may have not been encountered earlier in the learning phase.

Usage

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amdai(X, cls, model = "qda")

Arguments

X

the learning data

cls

the known labels for the learning data

model

the model to be used among "qda" or "lda". The default model is "qda".

Value

the function returns a QDA or LDA classifier to be used within the predict function.

Author(s)

Charles Bouveyron

References

C. Bouveyron, Adaptive mixture discriminant analysis for supervised learning with unobserved classes, Journal of Classification, vol. 31(1), pp. 49-84, 2014.

Examples

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set.seed(12345)

## Data simulation
data(iris)
Z.data = iris[,-5]
Z.cls = as.numeric(iris[,5])
Z.cls[as.numeric(iris[,5]==2)] = 3
Z.cls[as.numeric(iris[,5]==3)] = 2
N = 150

## Sampling
ind = sample(1:N,N)
X.data = Z.data[ind[1:(2*N/3)],]
X.cls = Z.cls[ind[1:(2*N/3)]]
X.data = X.data[X.cls!=3,]
X.cls = X.cls[X.cls!=3]
Y.data = Z.data[ind[(2*N/3+1):N],]
Y.cls = Z.cls[ind[(2*N/3+1):N]]

# Plotting the data
par(mfrow=c(2,3))#,cex.lab=0.75,cex.axis=0.75,cex.main=0.75,cex.sub=0.75)
pc = princomp(Z.data)
x = predict(pc,X.data)
y = predict(pc,Y.data)
plot(y,type='n',main='Learning data')
points(x[,1:2],col=X.cls+1,pch=19,main='Learning data')
y = predict(pc,Y.data)
plot(y[,1:2],col=1,pch=19,main='Test data')
plot(y[,1:2],col=Y.cls+1,pch=19,main='True labels of test data')

## Usual classification with QDA
c1 = qda(X.data,X.cls)
res1 = predict(c1,Y.data)
plot(y[,1:2],col=as.numeric(res1$class)+1,pch=19,main='QDA results')

## Classification with AMDAi
c2 = amdai(X.data,X.cls,model='qda')
B = rep(c(-Inf),5)
myPRMS <- vector(mode='list', length=7) # vector of lists!
for (i in 2:5){
  myPRMS[[i]] = predict(c2,Y.data,K=i)
	B[i] = myPRMS[[i]]$crit$bic
}
plot(2:5,B[2:5],type='b',xlab='Nb of components',ylab='AIC value',main='AIC values for AMDA')
res2 = myPRMS[[which.max(B)]]
plot(y[,1:2],col=res2$cls+1,pch=19,main='AMDA results')

## Classification results
cat("* Correct classification rates :\n")
cat("\tQDA:\t",sum(res1$class == Y.cls) / length(Y.cls),"\n")
print(table(res1$class,Y.cls))
cat("\tAMDAi:\t",sum(res2$cls == Y.cls) / length(Y.cls),"\n")
print(table(res2$cls,Y.cls))

adaptDA documentation built on May 30, 2017, 2:39 a.m.