unvec_mat: Transform vector data to image

In fMRItools: Routines for Common fMRI Processing Tasks

Transform vector data to image

Description

From a v \times p matrix of vectorized data and an m \times n image mask with v in-mask locations, create a list of p m \times n data arrays in which the mask locations are filled in with the vectorized data values.

Consider using abind::abind to merge the result into a single array.

Usage

unvec_mat(x, mask, fill_value = NA)

Arguments

x	v \times p matrix, where v is the number of voxels within a mask and p is the number of vectors to transform into matrix images.
mask	m \times n logical matrix in which v entries are TRUE and the rest are FALSE.
fill_value	Out-of-mask value in the output image. Default: NA.

Value

A list of masked values from x

Examples

x <- unvec_mat(
 cbind(seq(3), seq(2,4), seq(3,5)), 
 matrix(c(rep(TRUE, 3), FALSE), ncol=2),
 0
)
y <- array(c(1,2,3,0,2,3,4,0,3,4,5,0), dim=c(2,2,3))
stopifnot(identical(x[[1]], y[,,1]))
stopifnot(identical(x[[2]], y[,,2]))
stopifnot(identical(x[[3]], y[,,3]))

fMRItools documentation built on June 10, 2025, 9:09 a.m.