construct a regressor object — regressor • fmrireg

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
#> [1] TRUE

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))