Slot: Variable Key (variable_key)

For long orientation: the value in variable_column that selects this record's rows (e.g. tmax). Often, but not necessarily, equal to VariableIdentity.variable_name.

Tier: conditionally_core

Why this slot matters

Knowing which column discriminates variables is not enough — a consumer also needs the label value that selects this record's rows. Without the key, every row of a long file is a candidate and this record's values cannot be filtered out of the shared value column.

In plain terms

This is the label to filter on: keep only the rows where the variable column says, for example, tmax, and you have exactly this record's measurements. It usually matches the variable's short name, but does not have to.

URI: envar:slot/variable_key

Applicable Classes

Name	Description	Modifies Slot
DataLayout	How the companion data file (CSV / parquet) is laid out and how this record's...	no

Properties

Type and Range

Property	Value
Range	String
Domain Of	DataLayout

Cardinality and Requirements

Property	Value

Examples

Value
pm25_annual

Identifier and Mapping Information

Annotations

property	value
tier	conditionally_core
justification	Knowing which column discriminates variables is not enough — a consumer also needs the label value that selects this record's rows. Without the key, every row of a long file is a candidate and this record's values cannot be filtered out of the shared value column.
explanation	This is the label to filter on: keep only the rows where the variable column says, for example, `tmax`, and you have exactly this record's measurements. It usually matches the variable's short name, but does not have to.

Schema Source

from schema: https://w3id.org/linkml/microschemas/envar

Mappings

Mapping Type	Mapped Value
self	envar:variable_key
native	envar:variable_key

LinkML Source

name: variable_key
annotations:
  tier:
    tag: tier
    value: conditionally_core
  justification:
    tag: justification
    value: Knowing which column discriminates variables is not enough — a consumer
      also needs the label value that selects this record's rows. Without the key,
      every row of a long file is a candidate and this record's values cannot be filtered
      out of the shared value column.
  explanation:
    tag: explanation
    value: 'This is the label to filter on: keep only the rows where the variable
      column says, for example, `tmax`, and you have exactly this record''s measurements.
      It usually matches the variable''s short name, but does not have to.'
description: 'For long orientation: the value in `variable_column` that selects this
  record''s rows (e.g. `tmax`). Often, but not necessarily, equal to `VariableIdentity.variable_name`.'
title: Variable Key
examples:
- value: pm25_annual
  description: selects the PM2.5 rows in a long tract-level file
from_schema: https://w3id.org/linkml/microschemas/envar
see_also:
- https://doi.org/10.18637/jss.v059.i10
rank: 1000
domain_of:
- DataLayout
range: string