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}} = 2

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 layer
	for j=1,#checklist[depth],1 do -- loop over items ar current layer
		local subclasses
		if depth == 0 then
			subclasses = mw.wikibase.getBestStatements(checklist[depth][j],"P31") -- use P31 for layer 0
		else
			subclasses = mw.wikibase.getBestStatements(checklist[depth][j],"P279") -- use P279 for layers 1+
		end
		checklist[depth+1] = {} -- setup next layer of table
		for i,statement in ipairs(subclasses) do -- loop through items in next layer
			local newitem = statement.mainsnak.datavalue.value.id
			if newitem == value then
				isInstance = true
				break -- break away from loop if instance found
			else
				checklist[depth+1][#checklist[depth+1]+1] = newitem -- add item to next depth of checklist table
			end
		end
		if isInstance then
			break -- break away from loop if instance found
		end
	end
	return isInstance
end

function p.main(frame)
	local args = frame.args
	local pargs = frame:getParent().args
	maxdepth = 5
	depth = 0
	isInstance = false
	local qid = args.qid or pargs.qid
	checklist = {}
	checklist[0] = {qid}
	value = args.value or pargs.value
	while not isInstance and depth<maxdepth do
		checklayer(depth)
		depth = depth+1
	end
	if not isInstance then
		depth = -1 -- indicates not isInstance
	end
	return depth-1 -- return depth that item was found
end

return p