Module:Pop density

-- -- This module implements -- local p = {} local math_module = require( "Module:Math" ) local precision = math_module._precision

local function rnd(num, digits) -- This function implements return math_module._precision_format(tostring(num), tostring(digits)) end local unitnames = { ["km²"] = "km2", ["sqkm"] = "km2", ["km2"] = "km2", ["mi2"] = "sqmi", ["sqmi"] = "sqmi", ["acres"] = "acre", ["acre"] = "acre", ["ha"] = "ha", ["dunam"] = "dunam", ["m²"] = "m2", ["sqm"] = "m2", ["m2"] = "m2" } local unitmult = { ["km2"] = 1000000, ["sqmi"] = 2589988.110336, ["acre"] = 4046.8564224, ["ha"] = 10000, ["dunam"] = 1000, ["m2"] = 1 } local unitstr = { ["km2"] = 'km2', ["sqmi"] = 'sq mi', ["acre"] = 'acre', ["ha"] = 'ha', ["dunam"] = 'dunam', ["m2"] = 'm2' }

local function popdensity(pop, area1, areaunit1, areaunit2, prec, disp, flip) local dens1, prec1 = nil, nil local dens2, prec2 = nil, nil local str1, str2 = ,  local uniterror = '?Unknown unit?' if(pop ~=  and area1 ~= ) then -- pop and area are defined local popnum = tonumber(pop) if not popnum then error(string.format('Unable to convert population "%s" to a number', pop), 2) end local area1num = tonumber(area1) if not area1num then error(string.format('Unable to convert area "%s" to a number', area1), 2) end local dens1num = popnum/area1num local unit1 = unitnames[areaunit1] or nil local unit2 = unitnames[areaunit2] or nil prec1 = (prec ~= '') and tonumber(prec) or (1+math.log10(2*area1/(1/10^precision(pop)+pop/area1/10^precision(area1)))) dens1 = rnd(dens1num, math.floor(prec1 + 0.5)) if (unit1) then str1 = '/' .. unitstr[unit1] if(unit2) then -- convert local mult = unitmult[unit2]/unitmult[unit1] prec2 = prec1 - math.log10(mult) dens2 = rnd(dens1num*mult, math.floor(prec2 + 0.5)) str2 = '/' .. unitstr[unit2] elseif(areaunit2 ~= '') then if( disp ~= 'num' ) then dens2 = '?' else dens2 = '?' .. uniterror end str2 = '/' .. areaunit2 .. uniterror end elseif(areaunit1 ~= '') then if( disp ~= 'num' ) then dens2 = '?' else dens2 = '?' .. uniterror end if(unit2) then str2 = '/' .. unitstr[unit2] elseif(areaunit2 ~= '') then str2 = '/' .. areaunit2 .. uniterror end str1 = '/' .. areaunit1 .. uniterror end

-- form output if( str2 ~= '' ) then -- has a converted unit if( disp ~= 'num' ) then -- display input and output density numbers with units if( flip == 'on' ) then return dens2 .. str2 .. ' (' .. dens1 .. str1 .. ')' else return dens1 .. str1 .. ' (' .. dens2 .. str2 .. ')' end else -- display output density number without unit return dens2 end else -- no converted unit if( disp ~= 'num' ) then -- display input density number with unit return dens1 .. str1 else -- display input density number without unit return dens1 end end end return '' end

function p.density(frame) local args = (frame.args[3] ~= nil) and frame.args or frame:getParent.args return popdensity(args[1] or , args[2] or , args[3] or , args[4] or , args['prec'] or , args['disp'] or , args['flip'] or '') end

return p