dictionary.py

#!/usr/bin/env python3
"""The data dictionary — one definition per column, for both tables.

Authoritative. build.py renders it four ways and none of them is hand-written:

    data-dictionary.csv          machine-readable, one row per column
    docs/data-dictionary.md      the same as a document
    README.md "Fields" table     the dataset card
    README.md frontmatter        the Hub's dtype declarations

Adding a column to a builder without adding it here fails the build, which is the
point: the schema and its documentation cannot drift apart.

`unit` is the physical unit or "" for dimensionless and categorical columns.
`example` is illustrative, not drawn from the data.
"""

VERSION = "1.0"

# (name, dtype, unit, description)
CONTAINERS = [
    ("id", "string", "",
     "Stable slug, e.g. `euro-600x400x230`, `alc-600x400x310`, `vda-rklt-6429`"),
    ("type", "string", "",
     "`euro_stacking_container` · `attached_lid_container` · `vda_klt_container`"),
    ("type_label", "string", "", "Human-readable form of `type`"),
    ("common_names", "string", "",
     "Semicolon-separated search terms, ordered most standard to most colloquial, "
     "including regional ones (`Eurobehälter`, `bac gerbable`) and genericised vendor "
     "names (`Hudson box`). Search terms only — never discriminate families on them, "
     "see `guidance/naming.md`"),
    ("external_length_cm", "float64", "cm", "External length"),
    ("external_width_cm", "float64", "cm", "External width"),
    ("external_height_cm", "float64", "cm", "External height"),
    ("external_length_in", "float64", "in",
     "External length in inches. Always the derived side on this table — these "
     "nominal sizes are fixed in millimetres by the standards"),
    ("external_width_in", "float64", "in", "External width in inches, derived"),
    ("external_height_in", "float64", "in", "External height in inches, derived"),
    ("external_volume_l", "float64", "L", "L × W × H. **Not** what the box holds"),
    ("external_volume_gal", "float64", "US gal", "External volume in US liquid gallons"),
    ("internal_length_cm", "float64", "cm",
     "Typical internal length. Populated for every Euro row and for the two KLT sizes "
     "a vendor publishes; empty for ALCs, whose taper makes a single internal "
     "dimension meaningless"),
    ("internal_width_cm", "float64", "cm", "Typical internal width, same basis"),
    ("internal_height_cm", "float64", "cm", "Typical internal height, same basis"),
    ("internal_length_in", "float64", "in", "Typical internal length in inches, derived"),
    ("internal_width_in", "float64", "in", "Typical internal width in inches, derived"),
    ("internal_height_in", "float64", "in", "Typical internal height in inches, derived"),
    ("internal_dims_basis", "string", "",
     "Where those internal figures came from: `vendor_average_rule`, "
     "`vendor_published`, `not_published`, `not_published_tapered_walls`"),
    ("internal_dims_vendors", "int64", "",
     "How many **vendors** publish internal dimensions for this footprint. Vendors, "
     "not listings — one mould in five colours is one opinion"),
    ("typical_capacity_l", "float64", "L", "**The usable number.** Always populated"),
    ("typical_capacity_gal", "float64", "US gal",
     "Usable capacity in US liquid gallons"),
    ("vendor_capacity_low_l", "float64", "L",
     "Capacity implied by the least generous vendor's own published internal "
     "dimensions for this footprint. Empty where no vendor publishes any"),
    ("vendor_capacity_high_l", "float64", "L",
     "As above, most generous vendor. See `guidance/internal-dimensions.md`"),
    ("usable_ratio", "float64", "",
     "`typical_capacity_l / external_volume_l`"),
    ("capacity_basis", "string", "",
     "How the capacity was arrived at: `derived_from_internal_dims`, "
     "`vendor_nominal`, `published`, `derived_from_klt_ratio`"),
    ("lidded", "bool", "", "True where a lid is integral to the product (ALCs)"),
    ("lid_available_separately", "bool", "",
     "True where a lid exists but is a separate purchase"),
    ("nestable_when_empty", "bool", "",
     "True for ALCs; straight-walled boxes stack but do not nest"),
    ("typical_nesting_ratio", "float64", "",
     "Fraction of its own height a nested empty box saves. 0.75 for ALCs, **0 for "
     "everything else** — that is a fact about a straight-walled box, not missing data"),
    ("standard_conformant", "bool", "",
     "Whether the footprint conforms to a recognised module"),
    ("standard", "string", "", "Which one, stated precisely"),
    ("vda_4500_height", "bool", "",
     "Whether the external height is on the VDA KLT grid (147.5 / 213 / 280 mm)"),
    ("eur1_pallet_per_layer", "int64", "",
     "Boxes per layer on a 1200 × 800 Euro pallet, no overhang. The one column that "
     "reaches past the box itself — see Scope"),
    ("listings_observed", "int64", "",
     "How many rows in the `listings` table back this size — 0 means the row is a "
     "plausible interpolation, not something seen for sale"),
    ("notes", "string", "", "Per-row caveats. Read these"),
]

LISTINGS = [
    ("listing_id", "string", "", "Stable slug, `<vendor>-<sku or handle>`"),
    ("vendor", "string", "",
     "Salesbridges · Plastic Box Shop · Yosibox · Hudson Exchange"),
    ("vendor_country", "string", "", "ISO 3166-1 alpha-2 of the vendor's market"),
    ("product_name", "string", "", "The vendor's own product title, verbatim"),
    ("sku", "string", "", "Vendor SKU where published, else empty"),
    ("url", "string", "", "The listing, as captured on `captured_date`"),
    ("type", "string", "", "Family, assigned by this project — not the vendor's word"),
    ("native_unit", "string", "",
     "`metric` or `imperial`: which unit the vendor's own catalogue publishes in, and "
     "therefore which dimension columns are the figure and which are the conversion. "
     "See `guidance/units-and-us-vendors.md`"),
    ("external_length_cm", "float64", "cm", "External length as listed or converted"),
    ("external_width_cm", "float64", "cm", "External width as listed or converted"),
    ("external_height_cm", "float64", "cm", "External height as listed or converted"),
    ("external_length_in", "float64", "in", "External length; the vendor's own figure where `native_unit` is `imperial`"),
    ("external_width_in", "float64", "in", "External width, same basis"),
    ("external_height_in", "float64", "in", "External height, same basis"),
    ("internal_length_cm", "float64", "cm",
     "Internal length **as the vendor publishes it**, empty where they do not. 95 of "
     "121 rows carry these; vendors measure at different heights on a tapered box, "
     "which is why the typical table's figures are conservative"),
    ("internal_width_cm", "float64", "cm", "Internal width as published"),
    ("internal_height_cm", "float64", "cm", "Internal height as published"),
    ("internal_length_in", "float64", "in", "Internal length in inches"),
    ("internal_width_in", "float64", "in", "Internal width in inches"),
    ("internal_height_in", "float64", "in", "Internal height in inches"),
    ("stated_capacity_l", "float64", "L",
     "The vendor's own capacity claim. Not recomputed — the point of this table is "
     "what they say"),
    ("stated_capacity_gal", "float64", "US gal",
     "The same in US gallons; the vendor's own figure for Hudson Exchange"),
    ("external_volume_l", "float64", "L", "L × W × H, computed here"),
    ("external_volume_gal", "float64", "US gal", "The same in US gallons"),
    ("usable_ratio", "float64", "",
     "`stated_capacity_l / external_volume_l` — what **this** vendor claims, not what "
     "the typical table concluded"),
    ("price", "float64", "",
     "As captured, in `currency`. An observation with a date on it, not a price feed"),
    ("currency", "string", "", "ISO 4217"),
    ("price_includes_vat", "bool", "",
     "Whether the captured price is VAT-inclusive. Differs by market — UK and NL "
     "retail inclusive, US exclusive"),
    ("pack_quantity", "int64", "",
     "Units in the pack the price refers to. Multipacks and pallet deals are common"),
    ("unit_price", "float64", "", "`price / pack_quantity`"),
    ("captured_date", "string", "", "ISO 8601 date the listing was read"),
    ("notes", "string", "", "Per-row caveats, including non-conforming footprints"),
]

TABLES = {
    "containers": ("containers.csv", CONTAINERS),
    "listings": ("listings.csv", LISTINGS),
}

DTYPES = {name: dtype for _, cols in TABLES.values() for name, dtype, _, _ in cols}


def check(table: str, fields: list[str]) -> None:
    """Fail the build if a builder's columns and this dictionary disagree."""
    _, cols = TABLES[table]
    documented = [c[0] for c in cols]
    if documented != list(fields):
        missing = [f for f in fields if f not in documented]
        extra = [f for f in documented if f not in fields]
        raise SystemExit(
            f"{table}: dictionary and CSV columns disagree.\n"
            f"  undocumented in dictionary.py: {missing or 'none'}\n"
            f"  documented but not emitted:    {extra or 'none'}\n"
            f"  (order matters too — CSV order is {list(fields)})"
        )