Stream an operation over spatial maps — execute

Unlike collect_spatial_maps(), execute_spatial() holds only one input map at a time. The callback result is retained, so callers remain responsible for keeping returned values appropriately small.

Usage

execute_spatial(
  x,
  observations = NULL,
  FUN,
  ...,
  assay = active_assay(x),
  path = c("auto", "native", "reconstruct"),
  memory_budget = getOption("fmridataset.spatial_budget", 512 * 1024^2)
)

Arguments

x: An fmri_frame or view.
observations: Observation IDs or integer positions.
FUN: Function receiving map and observation_id.
...: Additional arguments passed to FUN.
assay: Assay name.
path: One of "auto", "native", or "reconstruct".
memory_budget: Maximum estimated peak bytes for one input spatial map plus its packed read, conversion, and reconstruction buffers.

Value

A list of callback results in requested observation order.

Examples

sp <- volume_space(dim = c(2L, 2L, 1L), affine = diag(4), support = 1:4)
frame <- fmri_frame(
  assays = list(signal = memory_source(matrix(seq_len(12), 3, 4))),
  observations = data.frame(.obs_id = sprintf("obs-%d", 1:3)),
  space = sp,
  active_assay = "signal"
)
execute_spatial(frame, c(1L, 2L), function(map, observation_id) observation_id)
#> [[1]]
#> [1] "obs-1"
#> 
#> [[2]]
#> [1] "obs-2"
#>