alffmap: alffmap

In neuroconductor/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

Description

Amplitude of Low Frequency Fluctuations (ALFF; Zang et al., 2007) and fractional Amplitude of Low Frequency Fluctuations (f/ALFF; Zou et al., 2008) are related measures that quantify the amplitude of low frequency oscillations (LFOs). This function outputs ALFF and fALFF for the input.

Usage

alffmap(
  x,
  flo = 0.01,
  fhi = 0.1,
  tr = 1,
  detrend = TRUE,
  takesqrt = FALSE,
  kernel
)

Arguments

x	input vector for the time series of interest
flo	low frequency, typically 0.01
fhi	high frequency, typically 0.1
tr	the period associated with the vector x (inverse of frequency)
detrend	detrend the input time series
takesqrt	take the sqrt of the computed values
kernel	smoothing kernel in estimate, see spec.pgram

Value

vector is output showing ALFF and fALFF values

Author(s)

Avants BB

Examples

set.seed(1)
mat <- matrix(rnorm(3000),ncol=50)
fallf = apply( mat, FUN=alffmap, MARGIN=2 )
k = kernel("daniell", rep( 2, 3 ) )
fallf2 = apply( mat, FUN=alffmap, MARGIN=2, kernel=k )
testthat::expect_equal(mean(fallf2), 3.00367017972746)

neuroconductor/ANTsR documentation built on Oct. 11, 2020, 8:14 a.m.