Module:Chart

Module Chart exports two functions: bar chart and pie chart

Note - Template:Graph:Chart is an alternative template, that may be more suitable for your use case.

Drawing Bar charts: "bar chart"

Parameters

parameter name	what it does
delimiter	string to delimit multiple values when given. default to colon ( : ). normally you do not want to touch this, it's provided for the off-chance you'll want to use colon as part of one of the parameters.
width	number. if provided, must be at least 200. default: 500
height	number. if provided, must be at least 200. default: 350
group n	(where "n" is a number. use "group 1", "group 2" etc. for as many groups as there are in the graph) the values to be charted. see below.
tooltip n	tooltip to be associated with specific bar. If no tooltip for a specific bar is defined, and this bar has a link, then this link will be used as tooltip. Otherwise, the tooltip will be combined from the group name and the value, optionally with "units prefix" and "units suffix".
links n	links to articles to be associated with specific bar
stack	whether to stack the different groups on top of each other. do not specify to show bars side by side. Any non-empty value means "yes". To say "no", simply do not supply this parameter at all, or leave the value blank.
tooltip value accumulation	useful only with stack: when set to true, tooltip will show accumulated value of all blocks up to current one
colors	the colors used to denote the various groups. should have exactly as many values as # of groups. can be given as standard html-recognized color names, or using #xxx or #xxxxxx notation.
x legends	The legends for the X values. Wikicode, such as internal links or templates can be used.
hide group legends	if set to true, group legends will not be shown below chart. Any non-empty value means "yes". To say "no", simply do not supply this parameter at all, or leave the value blank.
scale per group	set to use separate Y- scale for each group. leave empty to use one scale for all groups. incompatible with "stack". Note that even if some of the scales are exactly the same, they will be drawn separately when this setting is on. Any non-empty value means "yes". To say "no", simply do not supply this parameter at all, or leave the value blank.
units prefix	used in tooltip. e.g., $, so values will show as "$500" instead of "500" in the tooltip
units suffix	ditto for units suffix. use, e.g. "Kg" so values will show as 88Kg instead of 88 in tooltip. underscore ("_") are replaced by spaces, to allow a space between the value and the suffix.
group names	names of different groups
y tick marks	number of tick marks on the y axis. if the value is negative or omitted, the module will attempt to automatically calculate a sensible number of tick marks.

Examples

Basic

{{ #invoke:Chart | bar chart
| group 1 = 40 : 50 : 60 : 20
| group 2 = 20 : 60 : 12 : 44
| group 3 = 55 : 14 : 33 : 5
| links 1 = Weapon : Spear : Knife
| links 2 = Armor : Flak vest : Plate armor
| links 3 = Animal : Boomalope : Polar bear
| tooltip 2 = tooltip 1 : tooltip 2 : tooltip 3 : tooltip 4
| colors = green : yellow : orange
| group names = Weapon : Armor : Animal
| x legends = Before : During : After : Post mortem
}}

10

20

30

40

50

60

Before

During

After

Post mortem

•   Weapon
•   Armor
•   Animal

Stacked

Here is the same graph, with more modest height and width, using "stack", and adding "units suffix" for good measure:

{{ #invoke:Chart | bar chart
| height = 250
| width = 300
| stack = 1
| group 1 = 40 : 50 : 60 : 20
| group 2 = 20 : 60 : 12 : 44
| group 3 = 55 : 14 : 33 : 5
| colors = green : yellow : orange
| group names = Apple : Banana : Orange
| units suffix = Kg
| x legends = Before : During : After : Post mortem
}}

25

50

75

100

125

150

Before

During

After

Post mortem

•   Apple
•   Banana
•   Orange

Scale per group

This option has been disabled. It was rarely used and broke in the last code update. Here is an example with large number of groups - mainly to test how it looks with large number of legends:

{{ #invoke:Chart | bar chart
| width = 800
| height = 550
| group 1 = 1:2:3:4:5:4:3:2:1
| group 2 = 1:2:3:4:5:4:3:2:1
| group 3 = 1:2:3:4:5:4:3:2:1
| group 4 = 1:2:3:4:5:4:3:2:1
| group 5 = 1:2:3:4:5:4:3:2:1
| group 6 = 1:2:3:4:5:4:3:2:1
| group 7 = 1:2:3:4:5:4:3:2:1
| group 8 = 1:2:3:4:5:4:3:2:1
| group 9 = 1:2:3:4:5:4:3:2:1
| group 10 = 1:2:3:4:5:4:3:2:1
| group 11 = 1:2:3:4:5:4:3:2:1
| group 12 = 1:2:3:4:5:4:3:2:1
| group 13 = 1:2:3:4:5:4:3:2:1
| group 14 = 1:2:3:4:5:4:3:2:1
| group 15 = 1:2:3:4:5:4:3:2:1
| group 16 = 1:2:3:4:5:4:3:2:1
| group 17 = 1:2:3:4:5:4:3:2:1
| group 18 = 1:2:3:4:5:4:3:2:1
| group 19 = 1:2:3:4:5:4:3:2:1
| group 20 = 1:2:3:4:5:4:3:2:1
| group 21 = 1:2:3:4:5:4:3:2:1
| colors = Silver:Gray:Black:Red:Maroon:Yellow:Olive:Lime:Green:Aqua:Teal:Blue:Navy:Fuchsia:Purple:ForestGreen:Tomato:LightSeaGreen:RosyBrown:DarkOliveGreen:MediumVioletRed
| group names = Alabama:Alaska:Arizona:Arkansas:California:Colorado:Connecticut:Delaware:Florida:Georgia:Hawaii:Idaho:Illinois:Indiana:Iowa:Kansas:Kentucky:Louisiana:Maine:Maryland:Massachusetts
| x legends = 1920 : 1930 : 1940: 1950 : 1960 : 1970 : 1990 : 2000 : 2010
| units prefix = $
| units suffix = _billion
| stack = 1
}}

25

50

75

100

125

150

1920

1930

1940

1950

1960

1970

1990

2000

2010

•   Alabama
•   Alaska
•   Arizona
•   Arkansas
•   California
•   Colorado
•   Connecticut
•   Delaware
•   Florida
•   Georgia
•   Hawaii
•   Idaho
•   Illinois
•   Indiana
•   Iowa
•   Kansas
•   Kentucky
•   Louisiana
•   Maine
•   Maryland
•   Massachusetts

If there are many values, x legends can be diluted by using delimiters with nothing in between:

{{ #invoke:Chart | bar chart
| group 1 = 1:2:3:4:5:6:7:8:9:10:11:12:13:14:15:16:17:18:19:20:21:22:23:24:25:26:27:28:29:30
:31:32:33:34:35:36:37:38:39:40:41:42:43:44:45:46:47:48:49:50:51:52:53:54:55:56:57:58:59
| units suffix = _Things
| group names = Some
| x legends = ::::1940::::::::::1950::::::::::1960::::::::::1970::::::::::1980::::::::::1990::::
}}

10

20

30

40

50

60

1940

1950

1960

1970

1980

1990

Drawing Pie charts: "pie chart"

Parameters

parameter name	what it does
delimiter	string to delimit multiple values when given. default to colon ( : ). normally you do not want to touch this, it's provided for the off-chance you'll want to use colon as part of one of the parameters.
radius	number. The radius of the pie in pixels
slices	Tuples, in parenthesis. Use delimiter inside the tuple: ( Value1 : Name1 : Color1 : Link1 ) ( Value2 : Name2 : Color2 : Link2 ) ... The values are numbers. The numbers can be integers or decimal fractions, or using the scientific notation: 7.24e6, 7,240,000, or 7240000.00 are all acceptable for 7 Million and 240 thousands. Names are strings. Colors are optional. you can use any Web colors, such as "red" or "#FF0000". Up to 26 default colors are defined, but if your pie has more than 26 slices, you must define the colors of slice #27 and up. Links can be external or internal links, including linking to internal anchors and paragraphs in the same article, like so: [[Article|Tooltip]] for internal link, [[#Paragraph name|Tooltip]] for linking to an anchor in same article, or [http://example.org Tooltip] for external link.
slice n	alternative syntax to "slices". n is the slice number, beginning with 1. make sure not to skip: if you define "slice 1", "slice 2", "slice 4", "slice 5"..., skipping slice 3, only the first two slices will be shown. this syntax is incompatible with "slices", i.e., they should not be used in conjunction in the same invocation. Using both "slices" and "slice n" in the same invocation will cause unpredictable results. The value is like a single "tuple" as explained above, but without the parenthesis: | slice 1 = Value1 : Name1 : Color1 : Link1 | slice 2 = Value2 : Name2 : Color2 : Link2 | ... This syntax allows you to use parenthesis in names, links, and colors.
percent	if used, the percentage of each slice will be calculated and added to the legend: so if you have two slices, like so: ( 1 : Younglings ) ( 3 : elders ), and use define "percent", the legends will become "Younglings: 1 (25%)" and "Elders: 3 (75%)", instead of simply "Younglings: 1" and "Elders: 3". Any non-empty value means "yes". To say "no", simply do not supply this parameter at all, or leave the value blank.
units prefix	used in the legend. e.g., defining "units prefix=$", values will show as "$500" instead of "500" in the legends
units suffix	ditto for units suffix. use, e.g. "Kg" so values will show as 88Kg instead of 88 in legend. underscore ("_") are replaced by spaces, to allow a space between the value and the suffix.
hide group legends	Setting to true prevents displaying of the group legends under the chart. Any non-empty value means "yes". To say "no", simply do not supply this parameter at all, or leave the value blank.

Examples

{{#invoke:Chart|pie chart
| radius = 150
| slices = 
    ( 1000000 : Awful ) 
    ( 2000000 : Poor  : gold) 
    ( 1440000 : Normal ) 
    ( 6.4e5 : Good : : [[Good]] )
    ( 750,000 : Excellent )
| units suffix = _Units
| percent = true
}}

•   Awful: 1,000,000 Units (17.2%)
•   Poor: 2,000,000 Units (34.3%)
•   Normal: 1,440,000 Units (24.7%)
•   Good: 640,000 Units (11.0%)
•   Excellent: 750,000 Units (12.9%)

{{#invoke:chart|pie chart
|radius= 200
|units suffix = _Units
| slice 1 = 1 : 1
| slice 2 = 7 : 7
| slice 3 = 8 : 8
| slice 4 = 9 : 9
| slice 5 = 10 : 10
| slice 6 = 11 : 11
| slice 7  = 12 : 12
| slice 8  = 13 : 13
| slice 9  = 14 : 14
| slice 10 = 15 : 15
| slice 11 = 16 : 16
| slice 12 = 17 : 17
| slice 13 = 18 : 18
| slice 14 = 19 : 19
| slice 15 = 20 : 20
| slice 16 = 21 : 21
| slice 17 = 22 : 22
| slice 18 = 23 : 23
| slice 19 = 24 : 24
| slice 20 = 25 : 25
| slice 21 = 26 : 26
| slice 22 = 27 : 27
| slice 23 = 28 : 28
| slice 24 = 29 : 29
| slice 25 = 30 : 30
| slice 26 = 31 : 31
| percent = true
}}

•   1: 1 Units (0.2%)
•   7: 7 Units (1.5%)
•   8: 8 Units (1.7%)
•   9: 9 Units (1.9%)
•   10: 10 Units (2.1%)
•   11: 11 Units (2.3%)
•   12: 12 Units (2.5%)
•   13: 13 Units (2.7%)
•   14: 14 Units (2.9%)
•   15: 15 Units (3.2%)
•   16: 16 Units (3.4%)
•   17: 17 Units (3.6%)
•   18: 18 Units (3.8%)
•   19: 19 Units (4.0%)
•   20: 20 Units (4.2%)
•   21: 21 Units (4.4%)
•   22: 22 Units (4.6%)
•   23: 23 Units (4.8%)
•   24: 24 Units (5.0%)
•   25: 25 Units (5.3%)
•   26: 26 Units (5.5%)
•   27: 27 Units (5.7%)
•   28: 28 Units (5.9%)
•   29: 29 Units (6.1%)
•   30: 30 Units (6.3%)
•   31: 31 Units (6.5%)

---

--[[
    keywords are used for languages: they are the names of the actual
    parameters of the template
]]

local keywords = {
    barChart = 'bar chart',
    pieChart = 'pie chart',
    width = 'width',
    height = 'height',
    stack = 'stack',
    colors = 'colors',
    group = 'group',
    xlegend = 'x legends',
    yticks = 'y tick marks',
    tooltip = 'tooltip',
    accumulateTooltip = 'tooltip value accumulation',
    links = 'links',
    defcolor = 'default color',
    scalePerGroup = 'scale per group',
    unitsPrefix = 'units prefix',
    unitsSuffix = 'units suffix',
    groupNames = 'group names',
    hideGroupLegends = 'hide group legends',
    slices = 'slices',
    slice = 'slice',
    radius = 'radius',
    percent = 'percent',

} -- here is what you want to translate

local defColors = mw.loadData("Module:Chart/Default colors")
local hideGroupLegends

local function nulOrWhitespace( s )
    return not s or mw.text.trim( s ) == ''
end

local function createGroupList( tab, legends, cols )
    if #legends > 1 and not hideGroupLegends then
        table.insert( tab, mw.text.tag( 'div' ) )
        local list = {}
        local spanStyle = "padding:0 1em;background-color:%s;border:1px solid %s;margin-right:1em;-webkit-print-color-adjust:exact;"
        for gi = 1, #legends do
            local span = mw.text.tag( 'span', { style = string.format( spanStyle, cols[gi], cols[gi] ) }, ' ' ) .. ' '..  legends[gi]
            table.insert( list, mw.text.tag( 'li', {}, span ) )
        end
        table.insert( tab,
            mw.text.tag( 'ul',
                {style="width:100%;list-style:none;column-width:12em;"},
                table.concat( list, '\n' )
            )
        )
        table.insert( tab, '</div>' )
    end
end

function pieChart( frame )
    local res, imslices, args = {}, {}, frame.args
    local radius
    local values, colors, names, legends, links = {}, {}, {}, {}, {}
    local delimiter = args.delimiter or ':'
    local lang = mw.getContentLanguage()

    function getArg( s, def, subst, with )
        local result = args[keywords[s]] or def or ''
        if subst and with then result = mw.ustring.gsub( result, subst, with ) end
        return result
    end

    function analyzeParams()
        function addSlice( i, slice )
            local value, name, color, link = unpack( mw.text.split( slice, '%s*' .. delimiter .. '%s*' ) )
            values[i] = tonumber( lang:parseFormattedNumber( value ) )
                or error( string.format( 'Slice %d: "%s", first item("%s") could not be parsed as a number', i, value or '', sliceStr ) )
            colors[i] = not nulOrWhitespace( color ) and color or defColors[i * 2]
            names[i] = name or ''
            links[i] = link
        end
        
        radius = getArg( 'radius', 150 )
        hideGroupLegends = not nulOrWhitespace( args[keywords.hideGroupLegends] )
        local slicesStr = getArg( 'slices' )
        local prefix = getArg( 'unitsPrefix', '', '_', ' ' )
        local suffix = getArg( 'unitsSuffix', '', '_', ' ' )
        local percent = args[keywords.percent]
        local sum = 0
        local i, value = 0
        for slice in mw.ustring.gmatch( slicesStr or '', "%b()" ) do
            i = i + 1
            addSlice( i, mw.ustring.match( slice, '^%(%s*(.-)%s*%)$' ) )
        end
        
        for k, v in pairs(args) do
            local ind = mw.ustring.match( k, '^' .. keywords.slice .. '%s+(%d+)$' )
            if ind then addSlice( tonumber( ind ), v ) end
        end
        
        for _, val in ipairs( values ) do sum = sum + val end
        for i, value in ipairs( values ) do
            local addprec = percent and string.format( ' (%0.1f%%)', value / sum * 100 ) or ''
            legends[i] = mw.ustring.format( '%s: %s%s%s%s', names[i], prefix, lang:formatNum( value ), suffix, addprec )
            links[i] = mw.text.trim( links[i] or mw.ustring.format( '[[#noSuchAnchor|%s]]', legends[i] ) )
        end
    end

    function addRes( ... )
        for _, v in pairs( { ... } ) do
            table.insert( res, v )
        end
    end

    function createImageMap()
        addRes( '{{#tag:imagemap|', 'Image:Circle frame.svg{{!}}' .. ( radius * 2 ) .. 'px' )
        addRes( unpack( imslices ) )
        addRes( 'desc none', '}}' )
    end

    function drawSlice( i, q, start )
        local color = colors[i]
        local angle = start * 2 * math.pi
        local sin, cos = math.abs( math.sin( angle ) ), math.abs( math.cos( angle ) )
        local wsin, wcos = sin * radius, cos * radius
        local s1, s2, w1, w2, w3, w4, width, border
        local style
        if q == 1 then
            border = 'left'
            w1, w2, w3, w4 = 0, 0, wsin, wcos
            s1, s2 = 'bottom', 'left'
        elseif q == 2 then
            border = 'bottom'
            w1, w2, w3, w4 = 0, wcos, wsin, 0
            s1, s2 = 'bottom', 'right'
        elseif q == 3 then
            border = 'right'
            w1, w2, w3, w4 = wsin, wcos, 0, 0
            s1, s2 = 'top', 'right'
        else
            border = 'top'
            w1, w2, w3, w4 = wsin, 0, 0, wcos
            s1, s2 = 'top', 'left'
        end

        local style = string.format( 'border:solid transparent;position:absolute;%s:%spx;%s:%spx;width:%spx;height:%spx', s1, radius, s2, radius, radius, radius )
        if start <= ( q - 1 ) * 0.25 then
            style = string.format( '%s;border:0;background-color:%s', style, color )
        else
            style = string.format( '%s;border-width:%spx %spx %spx %spx;border-%s-color:%s', style, w1, w2, w3, w4, border, color )
        end
        addRes( mw.text.tag( 'div', { style = style }, '' ) )
    end

    function createSlices()
        function coordsOfAngle( angle )
            return ( 100 + math.floor( 100 * math.cos( angle ) ) ) .. ' ' .. ( 100 - math.floor( 100 * math.sin( angle ) ) )
        end

        local sum, start = 0, 0
        for _, value in ipairs( values ) do sum = sum + value end
        for i, value in ipairs(values) do
            local poly = { 'poly 100 100' }
            local startC, endC =  start / sum, ( start + value ) / sum
            local startQ, endQ = math.floor( startC * 4 + 1 ), math.floor( endC * 4 + 1 )
            for q = startQ, math.min( endQ, 4 ) do drawSlice( i, q, startC ) end
            for angle = startC * 2 * math.pi, endC * 2 * math.pi, 0.02 do
                table.insert( poly,  coordsOfAngle( angle ) )
            end
            table.insert( poly, coordsOfAngle( endC * 2 * math.pi ) .. ' 100 100 ' .. links[i] )
            table.insert( imslices, table.concat( poly, ' ' ) )
            start = start + values[i]
        end
    end

    analyzeParams()
    if #values == 0 then error( "no slices found - can't draw pie chart" ) end
    addRes( mw.text.tag( 'div', { class = 'chart noresize', style = string.format( 'margin-top:0.5em;max-width:%spx;', radius * 2 ) } ) )
    addRes( mw.text.tag( 'div', { style = string.format( 'position:relative;min-width:%spx;min-height:%spx;max-width:%spx;overflow:hidden;', radius * 2, radius * 2, radius * 2 ) } ) )
    createSlices()
    addRes( mw.text.tag( 'div', { style = string.format( 'position:absolute;min-width:%spx;min-height:%spx;overflow:hidden;', radius * 2, radius * 2 ) } ) )
    createImageMap()
    addRes( '</div>' ) -- close "position:relative" div that contains slices and imagemap.
    addRes( '</div>' ) -- close "position:relative" div that contains slices and imagemap.
    createGroupList( res, legends, colors ) -- legends
    addRes( '</div>' ) -- close containing div
    return frame:preprocess( table.concat( res, '\n' ) )
end


function barChart( frame )
    local res = {}
    local args = frame.args -- can be changed to frame:getParent().args
    local values, xlegends, colors, tooltips, yscales = {}, {}, {}, {} ,{}, {}, {}
    local groupNames, unitsSuffix, unitsPrefix, links = {}, {}, {}, {}
    local width, height, yticks, stack, delimiter = 500, 350, -1, false, args.delimiter or ':'
    local chartWidth, chartHeight, defcolor, scalePerGroup, accumulateTooltip


    local numGroups, numValues
    local scaleWidth

    function validate()
        function asGroups( name, tab, toDuplicate, emptyOK )
            if #tab == 0 and not emptyOK then
                error( "must supply values for " .. keywords[name] )
            end
            if #tab == 1 and toDuplicate then
                for i = 2, numGroups do tab[i] = tab[1] end
            end
            if #tab > 0 and #tab ~= numGroups then
                error ( keywords[name] .. ' must contain the same number of items as the number of groups, but it contains ' .. #tab .. ' items and there are ' .. numGroups .. ' groups')
            end
        end

        -- do all sorts of validation here, so we can assume all params are good from now on.
        -- among other things, replace numerical values with mw.language:parseFormattedNumber() result


        chartHeight = height - 80
        numGroups = #values
        numValues = #values[1]
        defcolor = defcolor or 'blue'
        colors[1] = colors[1] or defcolor
        scaleWidth = scalePerGroup and 80 * numGroups or 100
        chartWidth = width -scaleWidth
        asGroups( 'unitsPrefix', unitsPrefix, true, true )
        asGroups( 'unitsSuffix', unitsSuffix, true, true )
        asGroups( 'colors', colors, true, true )
        asGroups( 'groupNames', groupNames, false, false )
        if stack and scalePerGroup then
            error( string.format( 'Illegal settings: %s and %s are incompatible.', keyword.stack, keyword.scalePerGroup ) )
        end
        for gi = 2, numGroups do
            if #values[gi] ~= numValues then error( keywords.group .. " " .. gi .. " does not have same number of values as " .. keywords.group .. " 1" ) end
        end
        if #xlegends ~= numValues then error( 'Illegal number of ' .. keywords.xlegend .. '. Should be exactly ' .. numValues ) end
    end

    function extractParams()
        function testone( keyword, key, val, tab )
            i = keyword == key and 0 or key:match( keyword .. "%s+(%d+)" )
            if not i then return end
            i = tonumber( i ) or error("Expect numerical index for key " .. keyword .. " instead of '" .. key .. "'")
            if i > 0 then tab[i] = {} end
            for s in mw.text.gsplit( val, '%s*' .. delimiter .. '%s*' ) do
                table.insert( i == 0 and tab or tab[i], s )
            end
            return true
        end

        for k, v in pairs( args ) do
            if k == keywords.width then
                width = tonumber( v )
                if not width or width < 200 then
                    error( 'Illegal width value (must be a number, and at least 200): ' .. v )
                end
            elseif k == keywords.height then
                height = tonumber( v )
                if not height or height < 200 then
                    error( 'Illegal height value (must be a number, and at least 200): ' .. v )
                end
            elseif k == keywords.stack then stack = true
            elseif k == keywords.yticks then yticks = tonumber(v) or -1
            elseif k == keywords.scalePerGroup then scalePerGroup = true
            elseif k == keywords.defcolor then defcolor = v
            elseif k == keywords.accumulateTooltip then accumulateTooltip = not nulOrWhitespace( v )
            elseif k == keywords.hideGroupLegends then hideGroupLegends = not nulOrWhitespace( v )
            else
                for keyword, tab in pairs( {
                    group = values,
                    xlegend = xlegends,
                    colors = colors,
                    tooltip = tooltips,
                    unitsPrefix = unitsPrefix,
                    unitsSuffix = unitsSuffix,
                    groupNames = groupNames,
                    links = links,
                    } ) do
                        if testone( keywords[keyword], k, v, tab )
                            then break
                        end
                end
            end
        end
    end

    function roundup( x ) -- returns the next round number: eg., for 30 to 39.999 will return 40, for 3000 to 3999.99 wil return 4000. for 10 - 14.999 will return 15.
        local ordermag = 10 ^ math.floor( math.log10( x ) )
        local normalized = x /  ordermag
        local top = normalized >= 1.5 and ( math.floor( normalized + 1 ) ) or 1.5
        return ordermag * top, top, ordermag
    end

    function calcHeightLimits() -- if limits were passed by user, use them, otherwise calculate. for "stack" there's only one limet.
        if stack then
            local sums = {}
            for _, group in pairs( values ) do
                for i, val in ipairs( group ) do sums[i] = ( sums[i] or 0 ) + val end
            end
            local sum = math.max( unpack( sums ) )
            for i = 1, #values do yscales[i] = sum end
        else
            for i, group in ipairs( values ) do yscales[i] = math.max( unpack( group ) ) end
        end
        for i, scale in ipairs( yscales ) do yscales[i] = roundup( scale * 0.9999 ) end
        if not scalePerGroup then for i = 1, #values do yscales[i] = math.max( unpack( yscales ) ) end end
    end

    function tooltip( gi, i, val )
        if tooltips and tooltips[gi] and not nulOrWhitespace( tooltips[gi][i] ) then return tooltips[gi][i], true end
        local groupName = not nulOrWhitespace( groupNames[gi] ) and groupNames[gi] .. ': ' or ''
        local prefix = unitsPrefix[gi] or unitsPrefix[1] or ''
        local suffix = unitsSuffix[gi] or unitsSuffix[1] or ''
        return mw.ustring.gsub(groupName .. prefix .. mw.getContentLanguage():formatNum( tonumber( val ) or 0 ) .. suffix, '_', ' '), false
    end

    function calcHeights( gi, i, val )
        local barHeight = math.floor( val / yscales[gi] * chartHeight + 0.5 ) -- add half to make it "round" instead of "trunc"
        local top, base = chartHeight - barHeight, 0
        if stack then
            local rawbase = 0
            for j = 1, gi - 1 do rawbase = rawbase + values[j][i] end -- sum the "i" value of all the groups below our group, gi.
            base = math.floor( chartHeight * rawbase / yscales[gi] ) -- normally, and especially if it's "stack", all the yscales must be equal.
        end
        return barHeight, top - base
    end

    function groupBounds( i )
        local setWidth = math.floor( chartWidth / numValues )
        local setOffset = ( i - 1 ) * setWidth
        return setOffset, setWidth
    end

    function calcx( gi, i )
        local setOffset, setWidth = groupBounds( i )
        if stack or numGroups == 1 then
            local barWidth = math.min( 38, math.floor( 0.8 * setWidth ) )
            return setOffset + (setWidth - barWidth) / 2, barWidth
        end
        setWidth = 0.85 * setWidth
        local barWidth = math.floor( 0.75 * setWidth / numGroups )
        local left = setOffset + math.floor( ( gi - 1 ) / numGroups * setWidth )
        return left, barWidth
    end

    function drawbar( gi, i, val, ttval )
        if val == '0' then return end -- do not show single line (borders....) if value is 0, or rather, '0'. see talkpage

        local color, tooltip, custom = colors[gi] or defcolor or 'blue', tooltip( gi, i, ttval or val )
        local left, barWidth = calcx( gi, i )
        local barHeight, top = calcHeights( gi, i, val )
        
        -- borders so it shows up when printing
        local style = string.format("position:absolute;left:%spx;top:%spx;height:%spx;min-width:%spx;max-width:%spx;background-color:%s;-webkit-print-color-adjust:exact;border:1px solid %s;border-bottom:none;overflow:hidden;",
                        left, top, barHeight-1, barWidth-2, barWidth-2, color, color)
        local link = links[gi] and links[gi][i] or ''
        local img = not nulOrWhitespace( link ) and mw.ustring.format( '[[File:Transparent.png|1000px|link=%s|%s]]', link, custom and tooltip or '' ) or ''
        table.insert( res, mw.text.tag( 'div', { style = style, title = tooltip, }, img ) )
    end


    function drawYScale()
        function drawSingle( gi, color, width, yticks, single )
            local yscale = yscales[gi]
            local _, top, ordermag = roundup( yscale * 0.999 )
            local numnotches = yticks >= 0 and yticks or
            		(top <= 1.5 and top * 4
            		or top < 4  and top * 2
                    or top)
            local valStyleStr =
                single and 'position:absolute;height=20px;text-align:right;vertical-align:middle;width:%spx;top:%spx;padding:0 2px'
                or 'position:absolute;height=20px;text-align:right;vertical-align:middle;width:%spx;top:%spx;left:3px;background-color:%s;color:white;font-weight:bold;text-shadow:-1px -1px 0 #000,1px -1px 0 #000,-1px 1px 0 #000,1px 1px 0 #000;padding:0 2px'
            local notchStyleStr = 'position:absolute;height=1px;min-width:5px;top:%spx;left:%spx;border:1px solid %s;'
            for i = 1, numnotches do
                local val = i / numnotches * yscale
                local y = chartHeight - calcHeights( gi, 1, val )
                local div = mw.text.tag( 'div', { style = string.format( valStyleStr, width - 10, y - 10, color ) }, mw.getContentLanguage():formatNum( tonumber( val ) or 0 ) )
                table.insert( res, div )
                div = mw.text.tag( 'div', { style = string.format( notchStyleStr, y, width - 4, color ) }, '' )
                table.insert( res, div )
            end
        end

        if scalePerGroup then
            local colWidth = 80
            local colStyle = "position:absolute;height:%spx;min-width:%spx;left:%spx;border-right:1px solid %s;color:%s"
            for gi = 1, numGroups do
                local left = ( gi - 1 ) * colWidth
                local color = colors[gi] or defcolor
                table.insert( res, mw.text.tag( 'div', { style = string.format( colStyle, chartHeight, colWidth, left, color, color ) } ) )
                drawSingle( gi, color, colWidth, yticks )
                table.insert( res, '</div>' )
            end
        else
            drawSingle( 1, 'black', scaleWidth, yticks, true )
        end
    end

    function drawXlegends()
        local setOffset, setWidth
        local legendDivStyleFormat = "position:absolute;left:%spx;top:10px;min-width:%spx;max-width:%spx;text-align:center;vertical-align:top;"
        local tickDivstyleFormat = "position:absolute;left:%spx;height:10px;width:1px;border-left:1px solid black;"
        for i = 1, numValues do
            if not nulOrWhitespace( xlegends[i] ) then
                setOffset, setWidth = groupBounds( i )
                -- setWidth = 0.85 * setWidth
                table.insert( res, mw.text.tag( 'div', { style = string.format( legendDivStyleFormat, setOffset + 5, setWidth - 10, setWidth - 10 ) }, xlegends[i] or '' ) )
                table.insert( res, mw.text.tag( 'div', { style = string.format( tickDivstyleFormat, setOffset + setWidth / 2 ) }, '' ) )
            end
        end
    end

    function drawChart()
        table.insert( res, mw.text.tag( 'div', { class = 'chart noresize', style = string.format( 'margin-top:1em;max-width:%spx;', width ) } ) )
        table.insert( res, mw.text.tag( 'div', { style = string.format("position:relative;min-height:%spx;min-width:%spx;max-width:%spx;", height, width, width ) } ) )

        table.insert( res, mw.text.tag( 'div', { style = string.format("float:right;position:relative;min-height:%spx;min-width:%spx;max-width:%spx;border-left:1px black solid;border-bottom:1px black solid;", chartHeight, chartWidth, chartWidth ) } ) )
        local acum = stack and accumulateTooltip and {}
        for gi, group in pairs( values ) do
            for i, val in ipairs( group ) do
                if acum then acum[i] = ( acum[i] or 0 ) + val end
                drawbar( gi, i, val, acum and acum[i] )
            end
        end
        table.insert( res, '</div>' )
        table.insert( res, mw.text.tag( 'div', { style = string.format("position:absolute;height:%spx;min-width:%spx;max-width:%spx;", chartHeight, scaleWidth, scaleWidth, scaleWidth ) } ) )
        drawYScale()
        table.insert( res, '</div>' )
        table.insert( res, mw.text.tag( 'div', { style = string.format( "position:absolute;top:%spx;left:%spx;width:%spx;", chartHeight, scaleWidth, chartWidth ) } ) )
        drawXlegends()
        table.insert( res, '</div>' )
        table.insert( res, '</div>' )
        createGroupList( res, groupNames, colors )
        table.insert( res, '</div>' )
    end

    extractParams()
    validate()
    calcHeightLimits()
    drawChart()
    return table.concat( res, "\n" )
end

return {
    ['bar-chart'] = barChart,
    [keywords.barChart] = barChart,
    [keywords.pieChart] = pieChart,
}