blocklens: Get block/run lengths

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

Get block/run lengths

Description

Get the number of scans or timepoints in each block/run of the dataset. Block lengths are used to:

• Define the temporal structure of the experiment by specifying scan counts and timing per run

• Allocate memory for data matrices by pre-allocating arrays based on scan counts

• Validate data dimensions across runs by checking against expected lengths

• Calculate global timing information by computing cumulative timing across runs

Usage

blocklens(x, ...)

Arguments

x	The object containing block information (typically a sampling_frame or dataset)
...	Additional arguments passed to methods

Value

A numeric vector where:

• Each element is the number of scans in a block or run

• Length equals the number of blocks/runs

• Values are positive integers

See Also

blockids(), split_by_block(), sampling_frame()

Other block_operations: blockids(), split_by_block()

Examples

# Create a sampling frame with varying run lengths
sframe <- sampling_frame(
  blocklens = c(100, 150, 100),  # Different length runs
  TR = 2
)

# Get number of scans per run
run_lengths <- blocklens(sframe)  # Returns: c(100, 150, 100)

# Use block lengths to create a dataset
total_scans <- sum(run_lengths)  # 350 total timepoints
X <- matrix(rnorm(total_scans * 10), total_scans, 10)  # 10 voxels
dset <- matrix_dataset(
  X,
  TR = 2,
  run_length = run_lengths
)

# Verify block lengths in dataset
dset_lengths <- blocklens(dset)

# Use lengths to create time vectors for each run
time_vectors <- lapply(run_lengths, function(len) seq(0, by = 2, length.out = len))

bbuchsbaum/fmrireg documentation built on March 1, 2025, 11:20 a.m.