Module:Pop density
 | This Lua module is used on approximately 10,000 pages and changes may be widely noticed. Test changes in the module's /sandbox or /testcases subpages, or in your own module sandbox. Consider discussing changes on the talk page before implementing them. |
Usage
{{#invoke:Pop density|density}}
Tracking category
See also
--
-- This module implements {{Pop density}}
--
local p = {}
local math_module = require( "Module:Math" )
local precision = math_module._precision
local function rnd(num, digits)
-- This function implements {{rnd}}
return math_module._precision_format(tostring(num), tostring(digits))
end
local function unitnames(areaunit)
if(areaunit == 'km²' or areaunit == 'sqkm' or areaunit == 'km2' ) then
return 'km2'
elseif( areaunit == 'mi2' or areaunit == 'sqmi') then
return 'sqmi'
else
return '<span class="error">Unknown unit</span>'
end
end
local function popdensity(pop, area1, areaunit1, areaunit2, prec, disp, flip)
local dens1, dens1, prec1 = nil, nil, nil
local dens2, dens2, prec2 = nil, nil, nil
local str1, str2 = '', ''
if(pop ~= '' and area1 ~= '') then
-- pop and area are defined
local dens1num = tonumber(pop)/tonumber(area1)
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 (unitnames(areaunit1) == 'km2') then
str1 = '/km<sup>2</sup>'
if(unitnames(areaunit2) == 'sqmi') then
-- convert per km2 to per sqmi
prec2 = prec1 - .41329777
dens2 = rnd(dens1num*2.589988110336, math.floor(prec2 + 0.5))
str2 = '/sq mi'
end
elseif(unitnames(areaunit1) == 'sqmi') then
str1 = '/sq mi'
if(unitnames(areaunit2) == 'km2') then
-- convert per sqmi to per km2
prec2 = prec1 + .41329777
dens2 = rnd(dens1num/2.589988110336, math.floor(prec2 + 0.5))
str2 = '/km<sup>2</sup>'
end
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 '<span class="error">Error</span>'
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