As in #21, define a spatial network graph G = {V,E} as a set of nodes V and edges E where each edge connects two nodes.
see notes below for objects and attributes
some opinions about file formats and how to store metadata, conventions to follow for ease of use:
nodes and edges of a single network can be stored in one GeoPackage with layers named nodes and edges (a railway network could be in rail.gpkg).
if nodes have associated polygon geometries, store them in an node_areas layer in the same GeoPackage, with node_id to link them (GeoPackage modelling guidelines have related guidance)
sources can be stored in a CSV or Excel sheet (taking care to have one table per sheet, consistent column naming)
asset_type definitions can be captured in two tables: one for asset_types (name, title) and one table for asset_type_attributes, linked to asset type by asset_type column.
Nodes
A node:
has a Point geometry
has a node_id String/UUID which should be unique within an analysis project
has an asset_type String which groups it with other assets sharing custom attributes
may have a source String which refers to a third-party dataset
may have a source_id which links it to an entry in a third-party dataset
may have an associated area Polygon that represents a site, building, or service area
may have conventional attributes to support analysis:
unit_cost: rehabilitation cost (units must be defined, may be made consistent across a project, e.g. million $USD in 2020)
cost_per_km2: rehabilitation cost if partial rehabilitation is possible per unit area
Edges
An edge:
has a LineString geometry
has an edge_id
has from_id and to_id referring to its start and end nodes
may have a length_km length in kilometres (which might otherwise be calculated from the geometry)
may be directed (True/False), if flows on the graph should only be allowed to traverse the edge in one direction
may have conventional attributes to support analysis:
unit_cost: rehabilitation cost if any damage is supposed to require full replacement
cost_per_km: rehabilitation cost per length damaged if partial repairs are possible
Asset types
An asset type:
has an asset_type short name or id, for use in network data to refer back to it
has a title human readable name that can be more descriptive
may have a description with more details or notes
has a list of attributes
name used as attribute key or column name, conventionally all in lower_snake_case
title human readable name that can be more descriptive
description human-readable description (spell out abbreviations)
unit units
dtype data type: boolean, integer, string, float, categorical
categories: list of options if dtype is categorical
Data sources
A data source:
has a source short name or id, for use in network data to refer back to it
has a title for a longer descriptive name or title
may have a description for an abstract or longer description or notes
may have a url link
may have a citation recommended citation
may have a contact.name
may have a contact.email
may have a release_date year or standard timestamp
For design ideas and similar approaches (particularly for data source/provenance schema):
As in #21, define a spatial network graph G = {V,E} as a set of nodes V and edges E where each edge connects two nodes.
nodesandedgesof a single network can be stored in one GeoPackage with layers namednodesandedges(a railway network could be inrail.gpkg).node_areaslayer in the same GeoPackage, withnode_idto link them (GeoPackage modelling guidelines have related guidance)sourcescan be stored in a CSV or Excel sheet (taking care to have one table per sheet, consistent column naming)asset_typedefinitions can be captured in two tables: one forasset_types(name, title) and one table forasset_type_attributes, linked to asset type byasset_typecolumn.Nodes
A node:
geometrynode_idString/UUID which should be unique within an analysis projectasset_typeString which groups it with other assets sharing custom attributessourceString which refers to a third-party datasetsource_idwhich links it to an entry in a third-party datasetareaPolygon that represents a site, building, or service areaunit_cost: rehabilitation cost (units must be defined, may be made consistent across a project, e.g. million $USD in 2020)cost_per_km2: rehabilitation cost if partial rehabilitation is possible per unit areaEdges
An edge:
geometryedge_idfrom_idandto_idreferring to its start and end nodeslength_kmlength in kilometres (which might otherwise be calculated from the geometry)directed(True/False), if flows on the graph should only be allowed to traverse the edge in one directionunit_cost: rehabilitation cost if any damage is supposed to require full replacementcost_per_km: rehabilitation cost per length damaged if partial repairs are possibleAsset types
An asset type:
asset_typeshort name or id, for use in network data to refer back to ittitlehuman readable name that can be more descriptivedescriptionwith more details or notesnameused as attribute key or column name, conventionally all inlower_snake_casetitlehuman readable name that can be more descriptivedescriptionhuman-readable description (spell out abbreviations)unitunitsdtypedata type: boolean, integer, string, float, categoricalcategories: list of options if dtype is categoricalData sources
A data source:
sourceshort name or id, for use in network data to refer back to ittitlefor a longer descriptive name or titledescriptionfor an abstract or longer description or notesurllinkcitationrecommended citationcontact.namecontact.emailrelease_dateyear or standard timestampFor design ideas and similar approaches (particularly for data source/provenance schema):