This is the core constructor for creating HRF objects in the refactored system. It takes a function `f(t)` and attaches standard HRF attributes. If `params` are provided, `as_hrf` creates a closure that captures these parameters, ensuring they are used during evaluation rather than relying on the function's defaults.
Usage
as_hrf(
f,
name = deparse(substitute(f)),
nbasis = 1L,
span = 24,
params = list()
)Arguments
- f
The function to be turned into an HRF object. It must accept a single argument `t` (time).
- name
The name for the HRF object. Defaults to the deparsed name of `f`.
- nbasis
The number of basis functions represented by `f`. Must be
>= 1. Defaults to 1L.- span
The nominal time span (duration in seconds) of the HRF. Must be positive. Defaults to 24.
- params
A named list of parameters associated with the HRF function `f`. When provided, `as_hrf` creates a closure that captures these parameters. Defaults to an empty list.
Examples
# Create a custom HRF from a function
custom_hrf <- as_hrf(function(t) exp(-t/5),
name = "exponential",
span = 20)
evaluate(custom_hrf, seq(0, 10, by = 1))
#> [1] 1.0000000 0.8187308 0.6703200 0.5488116 0.4493290 0.3678794 0.3011942
#> [8] 0.2465970 0.2018965 0.1652989 0.1353353
# Create HRF with specific parameters (closure captures them)
gamma_hrf <- as_hrf(hrf_gamma, params = list(shape = 8, rate = 1.2))
evaluate(gamma_hrf, seq(0, 20, by = 1))
#> [1] 0.000000e+00 2.569603e-04 9.906555e-03 5.098097e-02 1.150339e-01
#> [6] 1.652124e-01 1.783027e-01 1.579909e-01 1.211776e-01 8.324087e-02
#> [11] 5.241863e-02 3.076671e-02 1.703914e-02 8.987295e-03 4.547455e-03
#> [16] 2.220023e-03 1.050522e-03 4.836759e-04 2.173533e-04 9.558295e-05
#> [21] 4.122511e-05