knnImp {performanceEstimation}

Fill in NA values with the values of the nearest neighbours

Description

Function that fills in all NA values using the k Nearest Neighbours of each case with NA values. It uses the median/most frequent value within the neighbours to fill in the NAs.

Usage

knnImp(data, k = 10, scale = TRUE, distData = NULL)

Arguments

data

A data frame with the data set

k

The number of nearest neighbours to use (defaults to 10)

scale

Boolean setting if the data should be scale before finding the nearest neighbours (defaults to TRUE)

distData

Optionally you may sepecify here a data frame containing the data set that should be used to find the neighbours. This is usefull when filling in NA values on a test set, where you should use only information from the training set. This defaults to NULL, which means that the neighbours will be searched in data

Details

This function uses the k-nearest neighbours to fill in the unknown (NA) values in a data set. For each case with any NA value it will search for its k most similar cases and use the values of these cases to fill in the unknowns.

The function will use either the median (in case of numeric variables) or the most frequent value (in case of factors), of the neighbours to fill in the NAs.

Value

A data frame without NA values

Author(s)

Luis Torgo [e-mail]

References

Torgo, L. (2014) An Infra-Structure for Performance Estimation and Experimental Comparison of Predictive Models in R. arXiv:1412.0436 [cs.MS] http://arxiv.org/abs/1412.0436

See Also

na.omit

Examples

## Not run: 
data(algae,package="DMwR")
cleanAlgae <- knnImp(algae)
summary(cleanAlgae)

## End(Not run)