explode

Splits a column by separator into multiple rows. Creates one row per value, duplicating other fields.

Write with --output. A trailing path is not a positional argument.

# Explode comma-separated values
undatum explode data.csv --field tags --separator "," --output output.csv

# Explode pipe-separated values
undatum explode data.jsonl --field categories --separator "|" --output output.jsonl

Key options: --field, --separator, --output. Also accepts --table, --flatten-nested, --on-error, --error-log, and --quotechar (shared options).