write_connectomes_to_parquet: Write Connectomes to Parquet Files

In riemtan: Riemannian Metrics for Symmetric Positive Definite Matrices

Write Connectomes to Parquet Files

Description

Exports a list of SPD matrices (connectomes) to individual Parquet files with accompanying metadata.

Usage

write_connectomes_to_parquet(
  connectomes,
  output_dir,
  file_pattern = "matrix_%04d.parquet",
  subject_ids = NULL,
  provenance = NULL,
  overwrite = FALSE
)

Arguments

connectomes	A list of dppMatrix objects representing SPD matrices
output_dir	Path to output directory (will be created if it doesn't exist)
file_pattern	File naming pattern with %d placeholder for index (default: "matrix_%04d.parquet")
subject_ids	Optional vector of subject/sample identifiers (default: NULL)
provenance	Optional list containing data provenance information (default: NULL)
overwrite	If TRUE, overwrites existing directory (default: FALSE)

Details

Creates a directory structure:

• Individual Parquet files (one per matrix)

• metadata.json with dimensions, file pattern, and optional metadata

The metadata.json file contains:

• n_matrices: Number of matrices

• matrix_dim: Dimension p (matrices are p x p)

• file_pattern: Naming pattern for Parquet files

• subject_ids: Optional subject identifiers

• provenance: Optional provenance information

Value

Invisibly returns the path to the output directory

Examples

## Not run: 
# Create sample data
mats <- replicate(10, Matrix::pack(Matrix::Matrix(diag(5), sparse = FALSE)), simplify = FALSE)

# Write to Parquet
write_connectomes_to_parquet(
  mats,
  output_dir = "my_connectomes",
  subject_ids = paste0("subj_", 1:10),
  provenance = list(study = "Example Study", date = Sys.Date())
)

## End(Not run)

riemtan documentation built on Nov. 11, 2025, 1:06 a.m.