Module:Graph

Module with helper functions for the Graph extension.

Functions for templates

map

Creates a JSON object for <graph> to display a political map with colored highlights. In the article namespace the template Template:Graph:Map should be used instead. See its page for use cases.

Maps can be found at Special:Prefixindex/Module:Graph/ (for example WorldMap-iso2.json with country borders) and new maps should also be saved under Module:Graph/.

Parameters:

• basemap: Sets the base map. The map definitions must follow the TopoJSON format and if saved in Wikipedia are available for this module. Maps in the default directory Special:Prefixindex/Module:Graph/ such as WorldMap-iso2.json should only be referenced by their name while omitting the Module:Graph/ prefix to allow better portability. The parameter also accepts URLs, e.g. maps from other Wikipedia versions (the link should follow the scheme of //en.wikipedia.org/w/index.php?title=mapname&action=raw, i.e. protocol-relative without leading http/s and a trailing action=raw to fetch the raw content only). URLs to maps on external sites should be avoided for the sake of link stability, performance, security, and she be assumed to be blocked by the software or browser anyway.
• scale: the scaling factor of the map (default: 100)
• projection: the map projection to use. Supported values are listed at https://github.com/mbostock/d3/wiki/Geo-Projections. The default value is equirectangular for an equirectangular projection.
• ids of geographic entities: The actual parameter names depend on the base map. For example, for the above mentioned world map the ids are ISO country codes. The values can be either colors or numbers in case the geographic entities should be associated with numeric data: DE=lightblue marks Germany in light blue color, and DE=80.6 assigns Germany the value 80.6 (population in millions). In the latter case, the actual color depends on the following parameters.
  • colorScale: the color palette to use for the color scale. The palette must be provided as a comma-separated list of color values. The color values must be given either as #rgb/#rrggbb or by a CSS color name. Instead of a list, the built-in color palettes category10 and category20 can also be used.
  • scaleType: supported values are linear for a linear mapping between the data values and the color scale, log for a log mapping, pow for a power mapping (the exponent can be provided as pow 0.5), sqrt for a square-root mapping, and quantize for a quantized scale, i.e. the data is grouped in as many classes as the color palette has colors.
  • domainMin: lower boundary of the data values, i.e. smaller data values are mapped to the lower boundary
  • domainMax: upper boundary of the data values, i.e. larger data values are mapped to the upper boundary
  • legend: show color legend (does not work with quantize)
• defaultValue: default value for unused geographic entities. In case the id values are colors the default value is silver, in case of numbers it is 0.
• formatjson: format JSON object for better legibility

chart

Creates a JSON object for <graph> to display charts. In the article namespace the template Template:Graph:Chart should be used instead. See its page for use cases.

Parameters:

• width: width of the chart
• height: height of the chart
• type: type of the chart: line for line charts, area for area charts, and rect for (column) bar charts, and pie for pie charts. Multiple series can stacked using the stacked prefix, e.g. stackedarea.
• interpolate: interpolation method for line and area charts. It is recommended to use monotone for a monotone cubic interpolation – further supported values are listed at https://github.com/vega/vega/wiki/Marks#area.
• colors: color palette of the chart as a comma-separated list of colors. The color values must be given either as #rgb/#rrggbb/#aarrggbb or by a CSS color name. For #aarrggbb the aa component denotes the alpha channel, i.e. FF=100% opacity, 80=50% opacity/transparency, etc. (The default color palette is category10).
• xAxisTitle and yAxisTitle: captions of the x and y axes
• xAxisMin, xAxisMax, yAxisMin, and yAxisMax: minimum and maximum values of the x and y axes
• xAxisFormat and yAxisFormat: changes the formatting of the axis labels. Supported values are listed at https://github.com/mbostock/d3/wiki/Formatting and https://github.com/mbostock/d3/wiki/Time-Formatting. For example, the format % can be used to output percentages.
• xType and yType: Data types of the values, e.g. integer for integers, number for real numbers, date for dates (e.g. YYYY/MM/DD), and string for ordinal values.
• x: the x-values as a comma-separated list
• y or y1, y2, …: the y-values for one or several data series, respectively. For pie charts y2 denotes the radiuses of the corresponding sectors.
• legend: show legend (only works in case of multiple data series)
• y1Title, y2Title, …: defines the label of the respective data series in the legend
• linewidth: line width for line charts or distance between the pie segments for pie charts
• showValues: Additionally, output the y values as text. (Currently, only (non-stacked) bar and pie charts are supported.) The output can be configured used the following parameters provided as name1:value1, name2:value2:
  • format: Format the output according to https://github.com/mbostock/d3/wiki/Formatting#numbers for numbers and https://github.com/mbostock/d3/wiki/Time-Formatting for date/time.
  • fontcolor: text color
  • fontsize: text size
  • offset: move text by the given offset. For bar charts and pie charts with midangle this also defines if the text is inside or outside the chart.
  • angle (pie charts only): text angle in degrees or midangle (default) for dynamic angles based on the mid-angle of the pie sector.
• innerRadius: For pie charts: defines the inner radius to create a doughnut chart.
• formatjson: format JSON object for better legibility

Template wrappers

The functions mapWrapper and chartWrapper are wrappers to pass all parameters of the calling template to the respective map and chart functions.

Note: In the editor preview the graph extension creates a canvas element with vector graphics. However, when saving the page a PNG raster graphics is generated instead. {{#invoke:Graph

---

-- ATTENTION:  Please edit this code at https://de.wikipedia.org/wiki/Modul:Graph
--             This way all wiki languages can stay in sync. Thank you!
--
-- Version History:
--   2016-01-09 _PLEASE UPDATE when modifying anything_
--   2016-01-28 For maps, always use wikiraw:// protocol. https:// will be disabled soon.
--   2016-03-20 Allow omitted data for charts, labels for line charts with string (ordinal) scale at point location
--   2016-05-16 Added encodeTitleForPath() to help all path-based APIs graphs like pageviews

local p = {}

local baseMapDirectory = "Module:Graph/"

local function numericArray(csv)
	if not csv then return end

	local list = mw.text.split(csv, "%s*,%s*")
	local result = {}
	local isInteger = true
	for i = 1, #list do
		if list[i] == "" then
			result[i] = nil
		else
			result[i] = tonumber(list[i])
			if not result[i] then return end
			if isInteger then
				local int, frac = math.modf(result[i])
				isInteger = frac == 0.0
			end
		end
	end
	return result, isInteger
end

local function stringArray(csv)
	if not csv then return end

	return mw.text.split(csv, "%s*,%s*")
end

local function isTable(t) return type(t) == "table" end

local function copy(x)
	if type(x) == "table" then
		local result = {}
		for key, value in pairs(x) do result[key] = copy(value) end
		return result
	else
		return x
	end
end

function p.map(frame)
	-- map path data for geographic objects
	local basemap = frame.args.basemap or "WorldMap-iso2.json"
	-- scaling factor
	local scale = tonumber(frame.args.scale) or 100
	-- map projection, see https://github.com/mbostock/d3/wiki/Geo-Projections
	local projection = frame.args.projection or "equirectangular"
	-- defaultValue for geographic objects without data
	local defaultValue = frame.args.defaultValue
	local scaleType = frame.args.scaleType or "linear"
	-- minimaler Wertebereich (nur für numerische Daten)
	local domainMin = tonumber(frame.args.domainMin)
	-- maximaler Wertebereich (nur für numerische Daten)
	local domainMax = tonumber(frame.args.domainMax)
	-- Farbwerte der Farbskala (nur für numerische Daten)
	local colorScale = frame.args.colorScale or "category10"
	-- show legend
	local legend = frame.args.legend
	-- format JSON output
	local formatJson = frame.args.formatjson

	-- map data are key-value pairs: keys are non-lowercase strings (ideally ISO codes) which need to match the "id" values of the map path data
	local values = {}
	local isNumbers = nil
	for name, value in pairs(frame.args) do
		if mw.ustring.find(name, "^[^%l]+$") then
			if isNumbers == nil then isNumbers = tonumber(value) end
			local data = { id = name, v = value }
			if isNumbers then data.v = tonumber(data.v) end
			table.insert(values, data)
		end
	end
	if not defaultValue then
		if isNumbers then defaultValue = 0 else defaultValue = "silver" end
	end

	-- create highlight scale
	local scales
	if isNumbers then
		if colorScale == "category10" or colorScale == "category20" then else colorScale = stringArray(colorScale) end
		scales =
		{
			{
				name = "color",
				type = scaleType,
				domain = { data = "highlights", field = "v" },
				range = colorScale,
				nice = true
			}
		}
		if domainMin then scales[1].domainMin = domainMin end
		if domainMax then scales[1].domainMax = domainMax end

		local exponent = string.match(scaleType, "pow%s+(%d+%.?%d+)") -- check for exponent
		if exponent then
			scales[1].type = "pow"
			scales[1].exponent = exponent
		end
	end

	-- create legend
	if legend then
		legend =
		{
			{
				fill = "color",
				offset = 120,
				properties =
				{
					title = { fontSize = { value = 14 } },
					labels = { fontSize = { value = 12 } },
					legend =
					{
						stroke = { value = "silver" },
						strokeWidth = { value = 1.5 }
					}
				}
			}
		}
	end

	-- get map url
	local basemapUrl
	if (string.sub(basemap, 1, 10) == "wikiraw://") then
		basemapUrl = basemap
	else
		-- if not a (supported) url look for a colon as namespace separator. If none prepend default map directory name.
		if not string.find(basemap, ":") then basemap = baseMapDirectory .. basemap end
		basemapUrl = "wikiraw:///" .. mw.uri.encode(mw.title.new(basemap).prefixedText, "PATH")
	end

	local output =
	{
		version = 2,
		width = 1,  -- generic value as output size depends solely on map size and scaling factor
		height = 1, -- ditto
		data =
		{
			{
				-- data source for the highlights
				name = "highlights",
				values = values
			},
			{
				-- data source for map paths data
				name = "countries",
				url = basemapUrl,
				format = { type = "topojson", feature = "countries" },
				transform =
				{
					{
						-- geographic transformation ("geopath") of map paths data
						type = "geopath",
						value = "data",			-- data source
						scale = scale,
						translate = { 0, 0 },
						projection = projection
					},
					{
						-- join ("zip") of mutiple data source: here map paths data and highlights
						type = "lookup",
						keys = { "id" },      -- key for map paths data
						on = "highlights",    -- name of highlight data source
						onKey = "id",         -- key for highlight data source
						as = { "zipped" },    -- name of resulting table
						default = { v = defaultValue } -- default value for geographic objects that could not be joined
					}
				}
			}
		},
		marks =
		{
			-- output markings (map paths and highlights)
			{
				type = "path",
				from = { data = "countries" },
				properties =
				{
					enter = { path = { field = "layout_path" } },
					update = { fill = { field = "zipped.v" } },
					hover = { fill = { value = "darkgrey" } }
				}
			}
		},
		legends = legend
	}
	if (scales) then
		output.scales = scales
		output.marks[1].properties.update.fill.scale = "color"
	end

	local flags
	if formatJson then flags = mw.text.JSON_PRETTY end
	return mw.text.jsonEncode(output, flags)
end

local function deserializeXData(serializedX, xType, xMin, xMax)
	local x

	if not xType or xType == "integer" or xType == "number" then
		local isInteger
		x, isInteger = numericArray(serializedX)
		if x then
			xMin = tonumber(xMin)
			xMax = tonumber(xMax)
			if not xType then
				if isInteger then xType = "integer" else xType = "number" end
			end
		else
			if xType then error("Numbers expected for parameter 'x'") end
		end
	end
	if not x then
		x = stringArray(serializedX)
		if not xType then xType = "string" end
	end

	return x, xType, xMin, xMax
end

local function deserializeYData(serializedYs, yType, yMin, yMax)
	local y = {}
	local areAllInteger = true

	for yNum, value in pairs(serializedYs) do
		local yValues
		if not yType or yType == "integer" or yType == "number" then
			local isInteger
			yValues, isInteger = numericArray(value)
			if yValues then
				areAllInteger = areAllInteger and isInteger
			else
				if yType then
					error("Numbers expected for parameter '" .. name .. "'")
				else
					return deserializeYData(serializedYs, "string", yMin, yMax)
				end
			end
		end
		if not yValues then yValues = stringArray(value) end

		y[yNum] = yValues
	end
	if not yType then
		if areAllInteger then yType = "integer" else yType = "number" end
	end
	if yType == "integer" or yType == "number" then
		yMin = tonumber(yMin)
		yMax = tonumber(yMax)
	end

	return y, yType, yMin, yMax
end

local function convertXYToManySeries(x, y, xType, yType, seriesTitles)
	local data =
	{
		name = "chart",
		format =
		{
			type = "json",
			parse = { x = xType, y = yType }
		},
		values = {}
	}
	for i = 1, #y do
		local yLen = table.maxn(y[i])
		for j = 1, #x do
			if j <= yLen and y[i][j] then table.insert(data.values, { series = seriesTitles[i], x = x[j], y = y[i][j] }) end
		end
	end
	return data
end

local function convertXYToSingleSeries(x, y, xType, yType, yNames)
	local data = { name = "chart", format = { type = "json", parse = { x = xType } }, values = {} }

	for j = 1, #y do data.format.parse[yNames[j]] = yType end

	for i = 1, #x do
		local item = { x = x[i] }
		for j = 1, #y do item[yNames[j]] = y[j][i] end

		table.insert(data.values, item)
	end
	return data
end

local function getXScale(chartType, stacked, xMin, xMax, xType)
	if chartType == "pie" then return end

	local xscale =
	{
		name = "x",
		type = "linear",
		range = "width",
		zero = false, -- do not include zero value
		nice = true,  -- force round numbers for y scale
		domain = { data = "chart", field = "x" }
	}
	if xMin then xscale.domainMin = xMin end
	if xMax then xscale.domainMax = xMax end
	if xMin or xMax then xscale.clamp = true end
	if chartType == "rect" then
		xscale.type = "ordinal"
		if not stacked then xscale.padding = 0.2 end -- pad each bar group
	else
		if xType == "date" then xscale.type = "time"
		elseif xType == "string" then
			xscale.type = "ordinal"
			xscale.points = true
		end
	end

	return xscale
end

local function getYScale(chartType, stacked, yMin, yMax, yType)
	if chartType == "pie" then return end

	local yscale =
	{
		name = "y",
		type = "linear",
		range = "height",
		-- area charts have the lower boundary of their filling at y=0 (see marks.properties.enter.y2), therefore these need to start at zero
		zero = chartType ~= "line",
		nice = true
	}
	if yMin then yscale.domainMin = yMin end
	if yMax then yscale.domainMax = yMax end
	if yMin or yMax then yscale.clamp = true end
	if yType == "date" then yscale.type = "time"
	elseif yType == "string" then yscale.type = "ordinal" end
	if stacked then
		yscale.domain = { data = "stats", field = "sum_y" }
	else
		yscale.domain = { data = "chart", field = "y" }
	end

	return yscale
end

local function getColorScale(colors, chartType, xCount, yCount)
	if not colors then
		if (chartType == "pie" and xCount > 10) or yCount > 10 then colors = "category20" else colors = "category10" end
	end

	local colorScale =
	{
		name = "color",
		type = "ordinal",
		range = colors,
		domain = { data = "chart", field = "series" }
	}
	if chartType == "pie" then colorScale.domain.field = "x" end
	return colorScale
end

local function getAlphaColorScale(colors, y)
	local alphaScale
	-- if there is at least one color in the format "#aarrggbb", create a transparency (alpha) scale
	if isTable(colors) then
		local alphas = {}
		local hasAlpha = false
		for i = 1, #colors do
			local a, rgb = string.match(colors[i], "#(%x%x)(%x%x%x%x%x%x)")
			if a then
				hasAlpha = true
				alphas[i] = tostring(tonumber(a, 16) / 255.0)
				colors[i] = "#" .. rgb
			else
				alphas[i] = "1"
			end
		end
		for i = #colors + 1, #y do alphas[i] = "1" end
		if hasAlpha then alphaScale = { name = "transparency", type = "ordinal", range = alphas } end
	end
	return alphaScale
end

local function getValueScale(fieldName, min, max, type)
	local valueScale =
	{
		name = fieldName,
		type = type or "linear",
		domain = { data = "chart", field = fieldName },
		range = { min, max }
	}
	return valueScale
end

local function addInteractionToChartVisualisation(plotMarks, colorField, dataField)
	-- initial setup
	if not plotMarks.properties.enter then plotMarks.properties.enter = {} end
	plotMarks.properties.enter[colorField] = { scale = "color", field = dataField }

	-- action when cursor is over plot mark: highlight
	if not plotMarks.properties.hover then plotMarks.properties.hover = {} end
	plotMarks.properties.hover[colorField] = { value = "red" }

	-- action when cursor leaves plot mark: reset to initial setup
	if not plotMarks.properties.update then plotMarks.properties.update = {} end
	plotMarks.properties.update[colorField] = { scale = "color", field = dataField }
end

local function getPieChartVisualisation(yCount, innerRadius, outerRadius, linewidth, radiusScale)
	local chartvis =
	{
		type = "arc",
		from = { data = "chart", transform = { { field = "y", type = "pie" } } },

		properties =
		{
			enter = {
				innerRadius = { value = innerRadius },
				outerRadius = { },
				startAngle = { field = "layout_start" },
				endAngle = { field = "layout_end" },
				stroke = { value = "white" },
				strokeWidth = { value = linewidth or 1 }
			}
		}
	}

	if radiusScale then
		chartvis.properties.enter.outerRadius.scale = radiusScale.name
		chartvis.properties.enter.outerRadius.field = radiusScale.domain.field
	else
		chartvis.properties.enter.outerRadius.value = outerRadius
	end

	addInteractionToChartVisualisation(chartvis, "fill", "x")

	return chartvis
end

local function getChartVisualisation(chartType, stacked, colorField, yCount, innerRadius, outerRadius, linewidth, alphaScale, radiusScale, interpolate)
	if chartType == "pie" then return getPieChartVisualisation(yCount, innerRadius, outerRadius, linewidth, radiusScale) end

	local chartvis =
	{
		type = chartType,
		properties =
		{
			-- chart creation event handler
			enter =
			{
				x = { scale = "x", field = "x" },
				y = { scale = "y", field = "y" }
			}
		}
	}
	addInteractionToChartVisualisation(chartvis, colorField, "series")
	if colorField == "stroke" then
		chartvis.properties.enter.strokeWidth = { value = linewidth or 2.5 }
	end

	if interpolate then chartvis.properties.enter.interpolate = { value = interpolate } end

	if alphaScale then chartvis.properties.update[colorField .. "Opacity"] = { scale = "transparency" } end
	-- for bars and area charts set the lower bound of their areas
	if chartType == "rect" or chartType == "area" then
		if stacked then
			-- for stacked charts this lower bound is the end of the last stacking element
			chartvis.properties.enter.y2 = { scale = "y", field = "layout_end" }
		else
			--[[
			for non-stacking charts the lower bound is y=0
			TODO: "yscale.zero" is currently set to "true" for this case, but "false" for all other cases.
			For the similar behavior "y2" should actually be set to where y axis crosses the x axis,
			if there are only positive or negative values in the data ]]
			chartvis.properties.enter.y2 = { scale = "y", value = 0 }
		end
	end
	-- for bar charts ...
	if chartType == "rect" then
		-- set 1 pixel width between the bars
		chartvis.properties.enter.width = { scale = "x", band = true, offset = -1 }
		-- for multiple series the bar marking needs to use the "inner" series scale, whereas the "outer" x scale is used by the grouping
		if not stacked and yCount > 1 then
			chartvis.properties.enter.x.scale = "series"
			chartvis.properties.enter.x.field = "series"
			chartvis.properties.enter.width.scale = "series"
		end
	end
	-- stacked charts have their own (stacked) y values
	if stacked then chartvis.properties.enter.y.field = "layout_start" end

	-- if there are multiple series group these together
	if yCount == 1 then
		chartvis.from = { data = "chart" }
	else
		-- if there are multiple series, connect colors to series
		chartvis.properties.update[colorField].field = "series"
		if alphaScale then chartvis.properties.update[colorField .. "Opacity"].field = "series" end
		-- apply a grouping (facetting) transformation
		chartvis =
		{
			type = "group",
			marks = { chartvis },
			from =
			{
				data = "chart",
				transform =
				{
					{
						type = "facet",
						groupby = { "series" }
					}
				}
			}
		}
		-- for stacked charts apply a stacking transformation
		if stacked then
			table.insert(chartvis.from.transform, 1, { type = "stack", groupby = { "x" }, sortby = { "series" }, field = "y" } )
		else
			-- for bar charts the series are side-by-side grouped by x
			if chartType == "rect" then
				-- for bar charts with multiple series: each serie is grouped by the x value, therefore the series need their own scale within each x group
				local groupScale =
				{
					name = "series",
					type = "ordinal",
					range = "width",
					domain = { field = "series" }
				}

				chartvis.from.transform[1].groupby = "x"
				chartvis.scales = { groupScale }
				chartvis.properties = { enter = { x = { field = "key", scale = "x" }, width = { scale = "x", band = true } } }
			end
		end
	end

	return chartvis
end

local function getTextMarks(chartvis, chartType, outerRadius, scales, radiusScale, yType, showValues)
	local properties
	if chartType == "rect" then
		properties =
		{
			x = { scale = chartvis.properties.enter.x.scale, field = chartvis.properties.enter.x.field },
			y = { scale = chartvis.properties.enter.y.scale, field = chartvis.properties.enter.y.field, offset = -(tonumber(showValues.offset) or -4) },
			--dx = { scale = chartvis.properties.enter.x.scale, band = true, mult = 0.5 }, -- for horizontal text
			dy = { scale = chartvis.properties.enter.x.scale, band = true, mult = 0.5 }, -- for vertical text
			align = { },
			baseline = { value = "middle" },
			fill = { },
			angle = { value = -90 },
			fontSize = { value = tonumber(showValues.fontsize) or 11 }
		}
		if properties.y.offset >= 0 then
			properties.align.value = "right"
			properties.fill.value = showValues.fontcolor or "white"
		else
			properties.align.value = "left"
			properties.fill.value = showValues.fontcolor or "black"
		end
	elseif chartType == "pie" then
		properties =
		{
			x = { group = "width", mult = 0.5 },
			y = { group = "height", mult = 0.5 },
			radius = { offset = tonumber(showValues.offset) or -4 },
			theta = { field = "layout_mid" },
			fill = { value = showValues.fontcolor or "black" },
			baseline = { },
			angle = { },
			fontSize = { value = tonumber(showValues.fontsize) or math.ceil(outerRadius / 10) }
		}
		if (showValues.angle or "midangle") == "midangle" then
			properties.align = { value = "center" }
			properties.angle = { field = "layout_mid", mult = 180.0 / math.pi }

			if properties.radius.offset >= 0 then
				properties.baseline.value = "bottom"
			else
				if not showValues.fontcolor then properties.fill.value = "white" end
				properties.baseline.value = "top"
			end
		elseif tonumber(showValues.angle) then
			-- qunatize scale for aligning text left on right half-circle and right on left half-circle
			local alignScale = { name = "align", type = "quantize", domainMin = 0.0, domainMax = math.pi * 2, range = { "left", "right" } }
			table.insert(scales, alignScale)

			properties.align = { scale = alignScale.name, field = "layout_mid" }
			properties.angle = { value = tonumber(showValues.angle) }
			properties.baseline.value = "middle"
			if not tonumber(showValues.offset) then properties.radius.offset = 4 end
		end

		if radiusScale then
			properties.radius.scale = radiusScale.name
			properties.radius.field = radiusScale.domain.field
		else
			properties.radius.value = outerRadius
		end
	end

	if properties then
		if showValues.format then
			local template = "datum.y"
			if yType == "integer" or yType == "number" then template = template .. "|number:'" .. showValues.format .. "'"
			elseif yType == "date" then template = template .. "|time:" .. showValues.format .. "'"
			end
			properties.text = { template = "{{" .. template .. "}}" }
		else
			properties.text = { field = "y" }
		end

		local textmarks =
		{
			type = "text",
			properties =
			{
				enter = properties
			}
		}
		if chartvis.from then textmarks.from = copy(chartvis.from) end

		return textmarks
	end
end

local function getAxes(xTitle, xAxisFormat, xType, yTitle, yAxisFormat, yType, chartType)
	local xAxis, yAxis
	if chartType ~= "pie" then
		if xType == "integer" and not xAxisFormat then xAxisFormat = "d" end
		xAxis =
		{
			type = "x",
			scale = "x",
			title = xTitle,
			format = xAxisFormat
		}

		if yType == "integer" and not yAxisFormat then yAxisFormat = "d" end
		yAxis =
		{
			type = "y",
			scale = "y",
			title = yTitle,
			format = yAxisFormat
		}
	end

	return xAxis, yAxis
end

local function getLegend(legendTitle, chartType, outerRadius)
	local legend =
	{
		fill = "color",
		stroke = "color",
		title = legendTitle,
	}
	if chartType == "pie" then
		-- move legend from center position to top
		legend.properties = { legend = { y = { value = -outerRadius } } }
	end
	return legend
end

function p.chart(frame)
	-- chart width and height
	local graphwidth = tonumber(frame.args.width) or 200
	local graphheight = tonumber(frame.args.height) or 200
	-- chart type
	local chartType = frame.args.type or "line"
	-- interpolation mode for line and area charts: linear, step-before, step-after, basis, basis-open, basis-closed (type=line only), bundle (type=line only), cardinal, cardinal-open, cardinal-closed (type=line only), monotone
	local interpolate = frame.args.interpolate
	-- mark colors (if no colors are given, the default 10 color palette is used)
	local colors = stringArray(frame.args.colors)
	-- for line charts, the thickness of the line; for pie charts the gap between each slice
	local linewidth = tonumber(frame.args.linewidth)
	-- x and y axis caption
	local xTitle = frame.args.xAxisTitle
	local yTitle = frame.args.yAxisTitle
	-- x and y value types
	local xType = frame.args.xType
	local yType = frame.args.yType
	-- override x and y axis minimum and maximum
	local xMin = frame.args.xAxisMin
	local xMax = frame.args.xAxisMax
	local yMin = frame.args.yAxisMin
	local yMax = frame.args.yAxisMax
	-- override x and y axis label formatting
	local xAxisFormat = frame.args.xAxisFormat
	local yAxisFormat = frame.args.yAxisFormat
	-- show legend with given title
	local legendTitle = frame.args.legend
	-- show values as text
	local showValues = frame.args.showValues
	-- pie chart radiuses
	local innerRadius = tonumber(frame.args.innerRadius) or 0
	local outerRadius = math.min(graphwidth, graphheight)
	-- format JSON output
	local formatJson = frame.args.formatjson

	-- get x values
	local x
	x, xType, xMin, xMax = deserializeXData(frame.args.x, xType, xMin, xMax)

	-- get y values (series)
	local yValues = {}
	local seriesTitles = {}
	for name, value in pairs(frame.args) do
		local yNum
		if name == "y" then yNum = 1 else yNum = tonumber(string.match(name, "^y(%d+)$")) end
		if yNum then
			yValues[yNum] = value
			-- name the series: default is "y<number>". Can be overwritten using the "y<number>Title" parameters.
			seriesTitles[yNum] = frame.args["y" .. yNum .. "Title"] or name
		end
	end
	local y
	y, yType, yMin, yMax = deserializeYData(yValues, yType, yMin, yMax)

	-- create data tuples, consisting of series index, x value, y value
	local data
	if chartType == "pie" then
		-- for pie charts the second second series is merged into the first series as radius values
		data = convertXYToSingleSeries(x, y, xType, yType, { "y", "r" })
	else
		data = convertXYToManySeries(x, y, xType, yType, seriesTitles)
	end

	-- configure stacked charts
	local stacked = false
	local stats
	if string.sub(chartType, 1, 7) == "stacked" then
		chartType = string.sub(chartType, 8)
		if #y > 1 then -- ignore stacked charts if there is only one series
		stacked = true
		-- aggregate data by cumulative y values
		stats =
		{
			name = "stats", source = "chart", transform =
		{
			{
				type = "aggregate",
				groupby = { "x" },
				summarize = { y = "sum" }
			}
		}
		}
		end
	end

	-- create scales
	local scales = {}

	local xscale = getXScale(chartType, stacked, xMin, xMax, xType)
	table.insert(scales, xscale)
	local yscale = getYScale(chartType, stacked, yMin, yMax, yType)
	table.insert(scales, yscale)

	local colorScale = getColorScale(colors, chartType, #x, #y)
	table.insert(scales, colorScale)

	local alphaScale = getAlphaColorScale(colors, y)
	table.insert(scales, alphaScale)

	local radiusScale
	if chartType == "pie" and #y > 1 then
		radiusScale = getValueScale("r", 0, outerRadius)
		table.insert(scales, radiusScale)
	end

	-- decide if lines (strokes) or areas (fills) should be drawn
	local colorField
	if chartType == "line" then colorField = "stroke" else colorField = "fill" end

	-- create chart markings
	local chartvis = getChartVisualisation(chartType, stacked, colorField, #y, innerRadius, outerRadius, linewidth, alphaScale, radiusScale, interpolate)

	-- text marks
	local textmarks
	if showValues then
		if type(showValues) == "string" then -- deserialize as table
			local keyValues = mw.text.split(showValues, "%s*,%s*")
			showValues = {}
			for _, kv in ipairs(keyValues) do
				local key, value = mw.ustring.match(kv, "^%s*(.-)%s*:%s*(.-)%s*$")
				if key then showValues[key] = value end
			end
		end

		local chartmarks = chartvis
		if chartmarks.marks then chartmarks = chartmarks.marks[1] end
		textmarks = getTextMarks(chartmarks, chartType, outerRadius, scales, radiusScale, yType, showValues)
		if chartmarks ~= chartvis then
			table.insert(chartvis.marks, textmarks)
			textmarks = nil
		end
	end

	-- axes
	local xAxis, yAxis = getAxes(xTitle, xAxisFormat, xType, yTitle, yAxisFormat, yType, chartType)

	-- legend
	local legend
	if legendTitle then legend = getLegend(legendTitle, chartType, outerRadius) end

	-- construct final output object
	local output =
	{
		version = 2,
		width = graphwidth,
		height = graphheight,
		data = { data, stats },
		scales = scales,
		axes = { xAxis, yAxis },
		marks = { chartvis, textmarks },
		legends = { legend }
	}

	local flags
	if formatJson then flags = mw.text.JSON_PRETTY end
	return mw.text.jsonEncode(output, flags)
end

function p.mapWrapper(frame)
	return p.map(frame:getParent())
end

function p.chartWrapper(frame)
	return p.chart(frame:getParent())
end

-- Given an HTML-encoded title as first argument, e.g. one produced with {{ARTICLEPAGENAME}},
-- convert it into a properly URL path-encoded string
-- This function is critical for any graph that uses path-based APIs, e.g. PageViews graph
function p.encodeTitleForPath(frame)
	return mw.uri.encode(mw.text.decode(mw.text.trim(frame.args[1])	), 'PATH')
end

return p