split_fill-methods: Fill Disjoint Sets of Values with the Output of a Function

In neuroim2: Data Structures for Brain Imaging Data

Fill Disjoint Sets of Values with the Output of a Function

Description

This function splits an object into disjoint sets of values based on a factor, applies a specified function to each set, and returns a new object with the original values replaced by the function's output.

Usage

split_fill(x, fac, FUN)

## S4 method for signature 'NeuroVol,factor,function'
split_fill(x, fac, FUN)

Arguments

x	The object to split.
fac	The factor to split by.
FUN	The function used to summarize the sets.

Details

The FUN function can either return a scalar for each input vector or a vector equal to the length of the input vector. If it returns a scalar, every voxel in the set will be filled with that value in the output vector.

Value

An object of the same class as x, with values replaced by the output of FUN.

Examples

## Summarize with mean -- FUN returns a scalar
x <- NeuroSpace(c(10, 10, 10), c(1, 1, 1))
vol <- NeuroVol(rnorm(10 * 10 * 10), x)
fac <- factor(rep(1:10, length.out=1000))
ovol.mean <- split_fill(vol, fac, mean)
identical(dim(ovol.mean), dim(vol))
length(unique(as.vector(ovol.mean))) == 10

## Transform by reversing vector -- FUN returns a vector
ovol2 <- split_fill(vol, fac, rev)

neuroim2 documentation built on April 11, 2025, 5:46 p.m.