J: Create a vector, matrix or array of constants

In matlib: Matrix Functions for Teaching and Learning Linear Algebra and Multivariate Statistics

Create a vector, matrix or array of constants

Description

This function creates a vector, matrix or array of constants, typically used for the unit vector or unit matrix in matrix expressions.

Usage

J(..., constant = 1, dimnames = NULL)

Arguments

...	One or more arguments supplying the dimensions of the array, all non-negative integers
constant	The value of the constant used in the array
dimnames	Either NULL or the names for the dimensions.

Details

The "dimnames" attribute is optional: if present it is a list with one component for each dimension, either NULL or a character vector of the length given by the element of the "dim" attribute for that dimension. The list can be named, and the list names will be used as names for the dimensions.

Examples

J(3)
J(2,3)
J(2,3,2)
J(2,3, constant=2, dimnames=list(letters[1:2], LETTERS[1:3]))

X <- matrix(1:6, nrow=2, ncol=3)
dimnames(X) <- list(sex=c("M", "F"), day=c("Mon", "Wed", "Fri"))
J(2) %*% X      # column sums
X %*% J(3)      # row sums

matlib documentation built on Oct. 3, 2024, 1:09 a.m.