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Write Connectomes to Parquet Files

Source: R/parquet_io.R
write_connectomes_to_parquet.Rd

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)

Value

Invisibly returns the path to the output directory

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

Examples

if (FALSE) { # \dontrun{
# 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())
)
} # }