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block_hrf(normalize = TRUE) now computes each
basis’s absolute-peak normalization factor once, over the full blocked
span, using the fixed reference-grid policy of
normalize_hrf(..., "unit_peak_per_basis"). Previously each
call normalized against its requested times: a scalar evaluation could
become 1 even far from the peak, and the convolution and loop methods
could disagree. Scalar, vector, and chunked queries now retain the same
scale. Negative responses keep their sign and zero bases stay zero.
Rebuild designs and refit analyses that used normalized blocked
HRFs.
Every positive block_hrf() width is now integrated,
including widths below precision. Previously a short block
returned the unintegrated impulse response, creating a discontinuity
when width crossed the numerical step. width = 0 retains
the impulse convention. With summate = FALSE, the integral
is divided by width; with finite half_life, decay
attenuates the integrand but does not renormalize the averaging
weights.
hrf_bspline(), hrf_bspline_generator()
and HRF_BSPLINE now return a basis that is zero at both
ends of the span. Previously the last basis function equalled 1 at
span and was cut to 0 beyond it, so any weight on it
produced a step at the end of every response. The N
functions are now the interior functions of a clamped basis with
N + 2 functions (the same construction as
fmrireg::estimate_hrf()). Fitted coefficients and design
matrices built from these bases change; N must be at least
degree - 1. The tent basis
(hrf_tent_generator(), getHRF("tent"), and
hrf_bspline(degree = 1)) changes the same way: its tents
now peak at interior knots and the basis is zero at both ends (with
N = 5 over 24 s, peaks at 4, 8, …, 20 s instead of 4.8, …,
24 s).
hrf_weighted(method = "constant") now uses every
weight: n weights fill n bins. With
width, the window is split into n equal bins;
with times, weight i covers
[times[i], times[i + 1]) and the last bin is as wide as the
one before it. Previously the last weight only closed the window (and
was returned at the single time times[n]).
normalize = TRUE now makes all n weights sum
to 1. The method = "linear" form is unchanged. Weight
vectors that ended with a 0 as an end marker give the same values as
before, with span one bin longer.
Corrected the documentation of normalize in
hrf_boxcar() and hrf_weighted(). A unit-area
boxcar makes the GLM coefficient the integrated signal in the window,
not its mean, and a weighted HRF’s coefficient is a least-squares
amplitude, not a weighted mean. Behaviour is unchanged.
New hrf_palette() and matching ggplot2 scales
scale_colour_hrf(), scale_color_hrf() and
scale_fill_hrf(). The categorical palette has at least 3:1
contrast on white and near-black backgrounds and stays distinguishable
under common colour-vision deficiencies; the ordered palette is for
basis functions and parameter sweeps. All package plots use
them.
plot_hrfs() and plot_regressors() now
plot every column of a basis set (basis = "first" restores
the old behaviour), accept layout = "stack" for one panel
per curve, and choose the palette with palette.
plot_hrfs() gains reference for a dashed grey
comparison curve. plot_regressors() accepts a
regressor_set(), draws events as bars whose width is the
event duration, and shows scan-time values with
samples.
plot_regressors(), plot.Reg() and
plot.FeatureReg() evaluate with a precision matched to the
plotting grid by default (precision = NULL), so sharp HRF
edges are drawn where they occur.
Inside knitr documents, plot_hrfs() and
plot_regressors() return their result visibly and let knitr
print the plot, like a ggplot object. This lets document themes add
dark-mode figure versions. Assigning the result inside a chunk no longer
draws it; print it explicitly.
The base-graphics plot() methods use the same
palette, mark onsets with ticks on the time axis, and draw multi-basis
regressors one panel per basis function (layout = "overlay"
for the old style).
All vignette figures were redrawn with these helpers; the reconstruction section of the advanced vignette now fits basis weights to target HRFs.
Improved vignette plots for narrow screens: compact legends,
shared-axis panels for gamma libraries and reconstruction, and visible
light/dark series colors. Comparison helpers respect the active ggplot2
theme and accept draw = FALSE for customization or vignette
auto-printing.
Fixed clipped peak annotations and respected onset transparency in event and feature-regressor plots. Clarified the spline example’s 24-second support without changing its evaluated values.
Updated the website and vignettes to albersdown 2.1.0. Vignettes now use its self-contained output format with light, dark, and phone-sized figures, replacing the copied theme assets. Figure resolution is limited to keep the source package compact.
Added feature_regressor() for continuously sampled
features (for example RMS energy). Each sample is a zero-order-hold bin
of width dt, with optional pre-convolution centering and scaling. This
is the continuous analogue of an amplitude-modulated event train, not a
list of trials.
Added fixed-scale HRF normalization with
normalize_hrf() and the hrf_norm argument to
gen_hrf() and getHRF(). Modes include
Nilearn/SPM reference-grid scaling, unit peak, unit integral, and
independent per-basis unit peaks. The existing
normalise_hrf() and normalize = TRUE
interfaces retain their per-basis unit-peak behavior.
Factored the duplicated single-basis / multi-basis branching in
block_hrf(), evaluate.HRF(), and
normalise_hrf() into three internal helpers
(.weighted_combine, .normalise_result,
.get_peaks). No user-visible behavior change.
The package carried four evaluation engines. conv
provided the best speed/accuracy tradeoff in development benchmarks, so
there is now one compiled convolution engine.
method = "conv" remains the default and is the only
compiled convolution engine. It avoids FFT zero-padding overhead and is
substantially faster than loop on large designs; exact
speedups depend on design size, basis count, and
precision.
method = "fft" and method = "Rconv" are
deprecated. They now evaluate via conv and warn. The FFT
engine never repaid its zero-padding, because the HRF is short relative
to the sampled design, and it was the only method that could fail
outright (on an internal FFT size above ~1e7). Rconv was an
R reimplementation of conv that silently fell back to
loop whenever the grid was irregular or durations varied.
Both implementations have been removed.
method = "loop" is retained as the reference
implementation. It can be more accurate at a given
precision because event onsets are evaluated directly, and
it remains the automatic fallback for regressors built from a list of
per-event HRFs.
Event onsets and block edges are no longer snapped to the
internal grid. Each is placed at its exact sub-bin position,
substantially reducing off-grid error at the default
precision = 0.33. Blocks are projected onto the linear hat
basis, preserving trapezoid accuracy while keeping the exact edge
placement.
method = "loop" no longer truncates blocked events
at hrf_span. It now extends to
hrf_span + duration, removing a residual error that did not
shrink as precision decreased. Its support calculation no
longer assumes a multi-point regular grid, so one-point and irregular
grids work as well. Blocks whose onset precedes the requested grid are
retained when their duration carries the response into it.
Let the generated Rcpp wrapper translate native exceptions after
C++ stack unwinding, removing the remaining direct
Rf_error() call (issue #42).
Clarified that summate = FALSE computes a temporal
average, whose peak can decrease for longer blocks;
normalize = TRUE controls unit-peak scaling (issue
#49).
Preserved parameter metadata in closed HRF constructors and decorators without incorrectly warning that the captured parameters would be ignored.
Fixed loop-based block regressors integrating the kernel beyond its declared span, where the convolution engine already truncated it. The restored SPMG undershoot exposed this existing tail discrepancy. Support is now applied before block integration on both paths.
Breaking: corrected the SPMG canonical positive
coefficient from 0.0833 to 1/120 and used the
exact undershoot coefficient 1/(6*15!).
HRF_SPMG1, HRF_SPMG2, and
HRF_SPMG3 now have the SPM double-gamma shape (about 8.9%
undershoot relative to peak, previously 0.6%). This changes both raw
scale and shape; existing analyses should be refitted.
Breaking: the third column of
HRF_SPMG3 is now a genuine response dispersion derivative,
holding positive-component mean and mass fixed and using SPM’s
(h(d) - h(d + 0.01))/0.01 sign/step convention. Previously
it was a second time derivative. deriv(HRF_SPMG3, ...)
follows the corrected basis. Temporal derivatives remain analytic. These
are raw, unorthogonalized continuous kernels; exact sampled SPM/Nilearn
design compatibility is not implied. Existing normalize,
normalise_hrf(), normalize_hrf(), and
hrf_norm scaling policies are unchanged. Coefficients and
derivative-based amplitude summaries must respect the selected scaling
and basis geometry.
Fixed issue #50: feature_regressor() now rejects
matrix and array inputs instead of silently flattening them into one
long feature. Pass one feature column at a time.
Addresses the defects reported in issue #45.
Breaking: epoch (duration > 0)
regressors are no longer scaled by 1/precision.
evaluate() on a Reg object summed microtime
samples of a unit-height boxcar without a step-size factor, so the
amplitude of every epoch regressor grew as the precision
argument shrank – at the default precision = 0.33 an epoch
column was inflated roughly 3.2x relative to the integral it was meant
to approximate. The compiled engines now apply the same trapezoid
quadrature evaluate.HRF() uses, so a block response is
amplitude * integral h(t - onset - u) du over the block and
converges as precision decreases. Point events
(duration = 0) are unaffected. Fitted betas from epoch
designs will change scale. Because this release also corrects response
shapes and event timing, model fits and t-statistics cannot be assumed
unchanged; rebuild design matrices and refit existing analyses.
Breaking: summate = FALSE now takes
effect on every evaluation method. It was silently ignored by the
conv (the default), fft, and
Rconv engines, which never received the flag; only
method = "loop" honoured it.
Breaking: evaluate.HRF() selects
its impulse and block branches on duration alone rather
than on duration < precision. A numerical setting could
previously decide which model was evaluated: at
precision = 0.2 a duration of 0.19 was treated as an
impulse and 0.20 as a block, a five-fold amplitude jump. Durations
smaller than precision are now integrated as
blocks.
The accepted evaluation methods (conv,
fft, Rconv, loop) now agree to
within quadrature error on block regressors; the deprecated names
fft and Rconv route to
conv.
hrf_sine() and hrf_fourier() no longer
error on a scalar t. vapply() dropped the
result to a plain vector when length(t) == 1, so the
support mask failed with “incorrect number of subscripts on matrix”.
This was reachable from public API via lag_hrf(),
block_hrf(), and getHRF("fourier").
HRF_BSPLINE and hrf_bspline_generator()
now place interior knots from span, fixed when the object
is constructed. splines::bs() was called without
knots= and fell back to quantiles of whatever
t was supplied, so the basis depended on the evaluation
grid and disagreed with hrf_bspline(). Evaluating on a
single time point produced a degenerate basis.
The internal Daguerre basis normalizes each column against a
fixed reference grid rather than against the caller’s t.
Including negative lags inflated the divisor and shrank every returned
value.
hrf_gaussian(), hrf_mexhat(),
hrf_inv_logit(), and hrf_lwu() return 0 for
t < 0, as the other kernels already did. The regressor
path masked negative lags itself, but block_hrf() and
lag_hrf() sample the shape function directly and mixed in
pre-onset values – up to 2% of peak for a blocked Mexican hat. Note that
hrf_mexhat() is discontinuous at t = 0 as a
result, since its formula is non-zero there.
fmrihrf wrapper, fmrihrf_cli(), and
install_cli().importFrom(utils, tail) to avoid R CMD
check NOTEs.hrf_bspline() support handling so values for
t > span (and t < 0) are zeroed instead
of wrapping to onset-like values.block_hrf() block integration to include
quadrature step-size scaling, making amplitudes stable across
precision.hrf_sine() and hrf_fourier() to
clamp support to [0, span] and return zero outside the
modeled window.normalise_hrf() to use fixed normalization
constants computed on the HRF support, avoiding data-dependent scaling
across evaluation grids.evaluate.HRF() block-duration summation to use
the same weighted integration scheme as block_hrf().evaluate.Reg(normalize = TRUE) to normalize
regressor outputs consistently across evaluation methods, including
single-trial regressors with different durations.block_hrf(summate = FALSE) to return normalized
block integration (for both single- and multi-basis HRFs) instead of the
legacy pointwise-maximum behavior.hrf_boxcar() function for simple boxcar (step
function) HRFs with optional normalization.hrf_weighted() function for arbitrary
weighted-window HRFs with constant or linear interpolation.regressor() now accepts a list of HRF objects for
trial-varying HRF designs.plot.Reg() method for visualizing regressor
objects.plot_regressors() for comparing multiple regressors
on one plot (ggplot2 or base R).plot_hrfs() for comparing multiple HRF shapes.print.HRF() method for concise HRF summaries.as_hrf() where parameters stored
in the params attribute were never used at evaluation time.
The fix creates a closure that properly captures and applies parameters
during evaluation.These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.