regressor: construct a regressor object

In bbuchsbaum/fmrireg: R package for the anlysis of fmri data

construct a regressor object

Description

construct a regressor object that can be used to generate regression variables from a set of onset times and a hemodynamic response function. A regressor can be evaluated at a set of times to generate a time-course appropriate for modeling an fMRI response.

Usage

regressor(
  onsets,
  hrf = HRF_SPMG1,
  duration = 0,
  amplitude = 1,
  span = 40,
  summate = TRUE
)

Arguments

onsets	the event onsets in seconds
hrf	a hemodynamic response function, e.g. HRF_SPMG1 or costum HRF
duration	duration of events (default is 0)
amplitude	scaling vector (default is 1)
span	the temporal window of the impulse response function (default is 24)
summate	whether to summate hrf amplitude as a function of the duration of an event.

Value

an S3 list of type regressor

Examples

reg <- regressor(c(10,12,14,16,18, 40), HRF_SPMG1, duration=3)
pred <- evaluate(reg, seq(0,100,by=2))
nbasis(reg) == 1

reg2 <- regressor(c(10,12,14,16,18, 40), HRF_SPMG1, duration=3, summate=FALSE)
pred2 <- evaluate(reg2, seq(0,100,by=2))
stopifnot(max(pred) > max(pred2))

bbuchsbaum/fmrireg documentation built on May 16, 2023, 10:56 a.m.