spray (version 1.0)

spray:

Description

Create, coerce, and test for sparse array objects

Usage

spray(M, x, addrepeats=FALSE)
spraymaker(L, addrepeats=FALSE)
is.spray(S)
as.spray(arg1, arg2, addrepeats=FALSE, offbyone=FALSE)
index(S)
value(S)
is_valid_spray(L)

Arguments

M

Integer matrix with rows corresponding to index positions

x

Numeric value with elements corresponding to spray entries

S

Object to be tested for being a spray

L

A list, nominally of two elements (index matrix and value) which is to be tested for acceptability to be coerce to class spray

arg1,arg2

Various arguments to be coerced to a spray

addrepeats

Boolean, with default FALSE meaning to check for repeated index rows and, if any are found, return an error

offbyone

In function as.spray(), when converting from an array. Argument offbyone is Boolean with default FALSE meaning to insert array elements in positions corresponding to index elements, and TRUE meaning to add one

Details

The user should use spray(), if a matrix of indices and vector of values is available, or as.spray() which tries hard to do the Right Thing (tm).

Function spraymaker() is the formal creator function, and it is written to take the output of the C++ routines and return a spray object.

Functions index() and value() are accessor methods.

Examples

S <- spray(diag(5))    # missing second argument interpreted as '1'.
as.array(S,offbyone=TRUE) # zero indices interpreted as ones.

M <- matrix(1:5,6,5) # note first row matches the sixth row

## Not run:  spray(M,1:6)  # will not work because addrepeats is not TRUE


spray(M,1:6,addrepeats=TRUE)  # 7=1:6 


S <- spray(matrix(1:7,5,7))
a <- as.array(S)    # will not work if any(M<1)
S1 <- as.spray(a)
stopifnot(S==S1)