ssc (version 1.0)

snnrce: Train the SNNRCE model

Description

Builds and trains a model to predict the label of instances, according to SNNRCE algorithm.

Usage

snnrce(x, y, dist = "matrix", alpha = 0.1)

Arguments

x

A object that can be coerced as matrix. This object have various interpretations depending on the value set in dist argument. See dist argument.

y

A vector with the labels of training instances. In this vector the unlabeled instances are specified with the value NA.

dist

Distance information. Valid options are:

• "matrix": this string indicates that x is a distance matrix.
• string: the name of a distance method available in proxy package. In this case x is interpreted as a matrix of instances.
• function: a function defined by the user that computes the distance between two vectors. This function is called passing the vectors in the firsts two arguments. If the function have others arguments, those arguments must be have default values. In this case x is interpreted as a matrix of instances.

alpha

Rejection threshold to test the critical region. Default is 0.1.

Value

The trained model stored in a list with the following named values:

References

Yu Wang, Xiaoyan Xu, Haifeng Zhao, and Zhongsheng Hua. Semisupervised learning based on nearest neighbor rule and cut edges. Knowledge-Based Systems, 23(6):547–554, 2010. ISSN 0950-7051. doi: http://dx.doi.org/10.1016/j.knosys.2010.03.012.

Examples

# This example is part of SNNRCE demo.
# Use demo(SNNRCE) to see all the examples.

## Load Wine data set
data(wine)

x <- wine[, -14] # instances without classes
y <- wine[, 14] # the classes
x <- scale(x) # scale the attributes

## Prepare data
set.seed(20)
# Use 50% of instances for training
tra.idx <- sample(x = length(y), size = ceiling(length(y) * 0.5))
xtrain <- x[tra.idx,] # training instances
ytrain <- y[tra.idx]  # classes of training instances
# Use 70% of train instances as unlabeled set
tra.na.idx <- sample(x = length(tra.idx), size = ceiling(length(tra.idx) * 0.7))
ytrain[tra.na.idx] <- NA # remove class information of unlabeled instances

# Use the other 50% of instances for inductive testing
tst.idx <- setdiff(1:length(y), tra.idx)
xitest <- x[tst.idx,] # testing instances
yitest <- y[tst.idx] # classes of testing instances

## Example: Using the Euclidean distance in proxy package.
m <- snnrce(xtrain, ytrain, dist = "Euclidean")
pred <- predict(m, xitest)
caret::confusionMatrix(table(pred, yitest))