gapfill (version 0.9.6-1)

Score: Score Columns of a Matrix Containing NAs by its Values

Description

Helper function for Predict used to score the columns of a matrix according to their values. The scoring of a given column is done by pair-wise comparisons with all other columns. The comparison of columns is done by pair-wise comparisons of the non-missing values. This procedure is robust to missing values, if all columns of the matrix have a similar (potentially shifted) distribution of values.

Usage

Score(mat)

Arguments

mat

Numeric matrix. May contain NA values.

Value

Numeric vector of length ncol(mat).

References

F. Gerber, R. de Jong, M. E. Schaepman, G. Schaepman-Strub, and R. Furrer (2018) in IEEE Transactions on Geoscience and Remote Sensing, pp. 1-13, 10.1109/TGRS.2017.2785240.

Examples

# NOT RUN {
mat <- rbind(c( 1,  2, NA),
             c(NA, NA,  1),
             c( 2, NA,  3),
             c( 1,  5, NA),
             c(NA,  2,  5))
s <- Score(mat)

## manual calculation in R
Mean <- function(x) mean(x, na.rm = TRUE)
sByHand <- c(Mean(c(Mean(mat[,1] > mat[,2]),
                    Mean(mat[,1] > mat[,3]))),
             Mean(c(Mean(mat[,2] > mat[,1]),
                    Mean(mat[,2] > mat[,3]))),
             Mean(c(Mean(mat[,3] > mat[,1]),
                    Mean(mat[,3] > mat[,2]))))
stopifnot(identical(s, sByHand))

# }