split

Splits TSV rows into multiple output files.

Behavior:

• Line count mode (--lines-per-file/-l): Writes a fixed number of data rows to each output file before starting a new one.
• Random assignment (--num-files/-n): Assigns each data row to one of N output files using a pseudo-random generator.
• Random assignment by key (--num-files/-n, --key-fields/-k): Uses selected fields as a key so that all rows with the same key are written to the same output file.
• Files are written to the directory given by --dir (default: current directory).
• File names are formed as: <prefix><index><suffix>.
• By default, existing files are rejected; use --append/-a to append to them.

Input:

• Reads from files or standard input.
• Files ending in .gz are transparently decompressed.

Output:

• Files are written to the directory specified by --dir.
• By default, output files are named <prefix><index><suffix>.

Header behavior:

• --header-in-out/-H: Treats the first line as header and writes it to every output file. The header is not counted against --lines-per-file.
• --header-in-only/-I: Treats the first line as header and does NOT write it to output files.

Field syntax:

• --key-fields/-k accepts 1-based field indices and ranges (e.g., 1,3-5).
• Run tva --help-fields for a full description shared across tva commands.

Examples:

1. Split into files with 1000 lines each tva split -l 1000 data.tsv --dir output/

2. Randomly assign rows to 5 files tva split -n 5 data.tsv --dir output/

3. Split by key field (same key goes to same file) tva split -n 5 -k 1 data.tsv --dir output/