This repository stores a comprehensive unit catalog for Cognite Data Fusion (CDF) with a focus on standardization, comprehensiveness, and consistency. The catalog is maintained in two primary JSON files:
units.json
: Contains a list of units with their metadata.unitSystems.json
: Contains various unit systems and their quantities.
Each item in the units.json
has the following structure:
{
"externalId": "string",
"name": "string",
"longName": "string",
"symbol": "string",
"aliasNames": ["string", ...],
"quantity": "string",
"conversion": {
"multiplier": "float",
"offset": "float"
},
"source": "string",
"sourceReference": "URL"
}
externalId
: The external identifier for the unit. Its structure follows the pattern{quantity}:{unit}
(e.g.,temperature:deg_c
), adhering to the snake_case convention.name
: The primary name of the unit (e.g.,DEG_C
).longName
: A descriptive name for the unit (e.g.,degree Celsius
).symbol
: The symbol for the unit (e.g.,°C
).aliasNames
: An array of possible aliases for the unit.quantity
: Specifies the physical quantity the unit measures (e.g.,Temperature
).conversion
: An object containing multiplier and offset values for converting between units.source
: The primary source of the unit (e.g.,qudt.org
).sourceReference
: A URL reference to the unit definition on an external source, if available.
Each item in the unitSystems.json
has the following structure:
{
"name": "string",
"quantities": [
{
"name": "string",
"unitExternalId": "string"
},
...
]
}
name
: The name of the unit system (e.g.,default
,SI
).quantities
: An array containing the physical quantities and their associated units in the system.
To ensure the integrity of the catalog, the following tests are conducted:
- Syntax Check: Every unit item in
units.json
must have the specified keys. - Unique IDs: All unit
externalIds
inunits.json
must be unique. - Reference Validation: There should be no references to non-existent unit
externalIds
inunitSystems.json
. - Default Quantities: All quantities must be present in the
unitSystems.json
for the default quantity. - Consistent References: All quantity references in
unitSystems.json
must exist inunits.json
. - Unique aliases: All pairs of (
alias
andquantity
) must be unique, for all aliases inaliasNames
. - ExternalId Format: All unit
externalIds
must follow the pattern{quantity}:{unit}
, where bothquantity
andunit
are in snake_case.
Some of the units are sourced from QUDT.org, which is licensed under the Creative Commons Attribution 4.0 International License.
These are marked with the qudt.org
source.
Copyright 2023 Cognite AS
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
This license applies to any code/data file in this repository, unless otherwise noted.
To maintain the consistency and quality of the unit catalog, please ensure any contributions adhere to the established structure and guidelines. Before submitting any additions or modifications, ensure that all tests pass.