--
-- 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 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"] = '平方公里',
["sqmi"] = '平方英里',
["acre"] = '英亩',
["ha"] = '公顷',
["dunam"] = '德南',
["m2"] = '平方米'
}
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 = '<sup>[[Template:Pop density|单位错误]]</sup>[[Category:采用不支持单位的人口密度公式]]'
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 = '人/' .. 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 = '人/' .. unitstr[unit2]
elseif(areaunit2 ~= '') then
if( disp ~= 'num' ) then
dens2 = '?'
else
dens2 = '?' .. uniterror
end
str2 = '人/' .. areaunit2 .. uniterror
end
elseif(areaunit1 ~= '') then
if( disp ~= 'num' ) then
dens2 = '?'
else
dens2 = '?' .. uniterror
end
if(unit2) then
str2 = '人/' .. unitstr[unit2]
elseif(areaunit2 ~= '') then
str2 = '人/' .. areaunit2 .. uniterror
end
str1 = '人/' .. areaunit1 .. uniterror
end
-- form output
if( str2 ~= '' ) then
-- has a converted unit
if( disp ~= 'num' and disp ~= 'table' ) 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
elseif( disp == 'table') then
return pop .. '||' .. area1 .. '||' .. dens1 .. '||' .. dens2
else
-- display output density number without unit
return dens2
end
else
-- no converted unit
if( disp ~= 'num' and disp ~= 'table' ) then
-- display input density number with unit
return dens1 .. str1
elseif( disp == 'table') then
return pop .. '||' .. area1 .. '||' .. dens1
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
