Module:Is instance

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Usage

{{#invoke:Is instance|main|qid=|value=}}

This module will use Wikidata properties instance of (P31) and subclass of (P279) to determine whether or not an entity is an instance of some other entity.

Example

For example:

• HMS Ark Royal (Q847672)
  • is an instance of light aircraft carrier (Q1185562), which
    • is a subclass of aircraft carrier (Q17205), which
      • is a subclass of warship (Q3114762), which
        • is a subclass of naval vessel (Q177597), which
          • is a subclass of ship (Q11446).

To know that HMS Ark Royal (Q847672) is an instance of ship (Q11446), you can use:

{{#invoke:Is instance|main|qid=Q847672|value=Q11446}} = 3

The output number indicates the minimum recursion depth to find the value required. An output of zero indicates that the item is not an instance.

Maximum depth

For performance considerations, the module will not go on searching indefinitely. The default maximum recursion depth is 5. If you want to change this, use the |maxdepth= parameter.

The above documentation is transcluded from Module:Is instance/doc. (edit | history)
Editors can experiment in this module's sandbox (edit | diff) and testcases (edit | run) pages.
Subpages of this module.

local p = {};

local function checklayer(depth) -- check subclasses of items at current depth
	checklist[depth+1] = {} -- setup next layer of table
	local j = 0
	for j = 1,#checklist[depth] do -- loop over items at current depth
		local property
		if depth == 1 then
			property = "P31" -- use P31 for depth 1
		else
			property = "P279" -- use P279 for depths 2+
		end
		local subclasses = mw.wikibase.getBestStatements(checklist[depth][j],property) -- get P31 or P279 statements
		for i,statement in ipairs(subclasses) do -- loop through items at next depth
			if statement.mainsnak.snaktype == 'value' then
				local newitem = statement.mainsnak.datavalue.value.id
				if newitem == value then
					isInstance = true
				else
					checklist[depth+1][#checklist[depth+1]+1] = newitem -- add item to next depth of checklist table
				end
			end
		end
	end
	return isInstance
end

function p.main(frame)
	local args = frame.args
	local pargs = frame:getParent().args
	value = args.value or pargs.value
	local qid = args.qid or pargs.qid or ""
	if qid == "" then
		qid = mw.wikibase.getEntityIdForCurrentPage()
	end
	if not qid then
		return 0
	end
	checklist = {{qid}}
	local md = args.maxdepth or pargs.maxdepth
	if md then
		maxdepth = tonumber(md)
	else
		maxdepth = 5
	end
	depth = 0 -- current depth
	isInstance = false -- assume false until match found
	while not isInstance and depth<maxdepth do
		depth = depth+1
		checklayer(depth)
	end
	if not isInstance then
		depth = 0 -- indicates not isInstance
	end
	return depth -- return depth that item was found
end

return p