Force index arrays into range

Forces an (integer) array to have entries in the range 1-n, by (i) taking the entries modulo n, then (ii) setting zero elements to n. Useful for modifying index arrays into a form suitable for use with magic squares.

Usage

process(x, n)

Arguments

x

Index array to be processed

n

Modulo of arithmetic to be used

Author

Robin K. S. Hankin

Examples

# extract the broken diagonal of magic.2np1(4) that passes
# through element [1,5]:

a <- magic.2np1(4)
index <- t(c(1,5)+rbind(1:9,1:9))
a[process(index,9)]
#> [1] 22 43 55 76 16 28 49 70  1