Property talk:P2442
Documentation
translation of the value of a measurement to different units
Description | translation of a measurement to a different unit | |||||||||
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Represents | conversion factor between units (Q110682638) | |||||||||
Data type | Quantity | |||||||||
Domain | According to this template:
items for units
According to statements in the property:
When possible, data should only be stored as statementsunit of measurement (Q47574) | |||||||||
Allowed values | number with standard units (note: this should be moved to the property statements) | |||||||||
Allowed units | Instances of: unit of measurement | |||||||||
Usage notes | Use P2370 for conversion to SI base or derived units. | |||||||||
Example | yard (Q482798) → 3 foot foot (Q3710) → 12 inch line (Q649848) → 10 tochka sazhen (Q2018709) → 3 arshin | |||||||||
Tracking: usage | Category:Pages using Wikidata property P2442 (Q26678446) | |||||||||
See also | conversion to SI unit (P2370), subdivision of this unit (P9059) | |||||||||
Lists |
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Proposal discussion | Proposal discussion | |||||||||
Current uses |
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List of violations of this constraint: Database reports/Constraint violations/P2442#Type Q47574, SPARQL
List of violations of this constraint: Database reports/Constraint violations/P2442#Scope, SPARQL
List of violations of this constraint: Database reports/Constraint violations/P2442#Entity types
List of violations of this constraint: Database reports/Constraint violations/P2442#allowed qualifiers, SPARQL
List of violations of this constraint: Database reports/Constraint violations/P2442#Conflicts with P31, SPARQL
This property is being used by: Please notify projects that use this property before big changes (renaming, deletion, merge with another property, etc.) |
Obtaining the output type when converting[edit]
The UI shows which units the various conversion factors correspond to. Where does that data come from? It isn't clear from querying the value of the property.
The datatype of the conversion factors are simply xsd:decimal.
- @Drrngrvy: The following query retrieves both magnitude and unit for the example of {{Q:79738}}:
select * where {
# gigabyte
wd:Q79738 p:P2442 / psv:P2442 [
wikibase:quantityAmount ?amount ;
wikibase:quantityUnit ?unit ;
] .
?unit rdfs:label ?unitLabel .
filter (lang(?unitLabel) = "en")
}
Toni 001 (talk) 18:12, 19 October 2019 (UTC)
Scope: Which conversion to include, and which not.[edit]
I'd like to better understand and define what the property could and should be used for, and what not. Background: I recently removed some conversions from say, light-years, kilometres, ... to, say, microinches, historical nautical miles, metres, ... . Those removals were motivated by different reasons, or a combination:
- conversion was wrong (missing a couple of 000, which can happen if someone enters very large or small numbers manually)
- conversion is already given as conversion to SI unit (P2370)
- conversion was to an item representing different units ("general topic about unit XYZ")
- conversion was from more-standard to less-standard
- #1 seems uncontroversial. If there is a credible source for the wrong value, then the statement could be kept but deprecated.
- #2 is justified by the usage message: "Use P2370 for conversion to SI base or derived units."
- #3 can be justified by semantic consistency: Topics / collections of different units on the one hand, and a particular unit, used in a certain geographical region in a certain time period, with one particular value on the other hand, are different concepts. They each deserve a separate item, with their type-specific set of properties.
- #4 could be read from the label of this property: Even though unit conversions are "symmetric" in the sense that one can convert back and forth, this property does not need to convert both "byte to gigabyte" and "gigabyte to byte". The last one is sufficient to establish a relation, from which other conversions can be derived.
Especially for the last point (#4) I'd like to collect possible use cases of this property. Analyzing them and listing the possible ways in which they can be solved might help us come to a consensus about how to use this property. Toni 001 (talk) 14:44, 5 October 2019 (UTC)