R.utils (version 2.3.0)

arrayIndex: Converts vector indices to array indices

Description

Converts vector indices to array indices assuming last array dimension to "move fastest", e.g. matrices are stored column by column.

Usage

"arrayIndex"(i, dim, ...)

Arguments

i

A vector of vector indices to be converted to array indices.

dim

A non-empty numeric vector specifying the dimension of the array.

...

Not used.

Value

Returns an integer matrix of length(i) rows and length(dim) columns.

References

[1] H. Bengtsson, Bayesian Networks - a self-contained introduction with implementation remarks, Master's Thesis in Computer Science, Mathematical Statistics, Lund Institute of Technology, 1999.

See Also

From R v2.11.0 there is arrayInd(), which does the same thing as this method. which() with argument arr.ind=TRUE.

Examples

# Single index
print(arrayIndex(21, dim=c(4,3,3)))

# Multiple indices
print(arrayIndex(20:23, dim=c(4,3,3)))

# Whole array
x <- array(1:30, dim=c(5,6))
print(arrayIndex(1:length(x), dim=dim(x)))

# Find (row,column) of maximum value
m <- diag(4-abs(-4:4))
print(arrayIndex(which.max(m), dim=dim(m)))