Module:Convert
Documentation for this module may be created at Module:Convert/doc
--[[
TODO Too many items to list, but following are some points:
- Output needs rather than space in several places.
- Some conversions require two outputs: {{convert|55|nmi|km mi}}.
- Some units have two values: {{convert|3.21|m|ftin}}.
]]--
--[[-----BEGIN DATA TABLE-----
Plan to write a program to generate the conversion tables below.
The input would be a text file in human-friendly format, and
the output would be the following tables.
When a lot of data is added, it might be useful to put this in another module.
Values from http://en.wikipedia.org/wiki/Conversion_of_units
Check with http://en.wikipedia.org/wiki/Template:Convert/list_of_units
]]--
local units = {
-- Each value is {converter_table, default_out_unit}.
lookup = function (self, unit)
-- If unit is known, return its converter_table, default_out_unit.
local t = self[unit]
if t == nil then
local msg = 'Unit %s not known[[Category:Convert unknown unit]]'
error(msg:format(unit))
end
return t
end,
utype = 1,
scale = 2,
offset = 3,
defaultunit = 4,
['kg'] = {'mass', 1, 0, 'lb'},
['lb'] = {'mass', 0.45359237, 0, 'kg'},
['m'] = {'length', 1, 0, 'ft'},
['km'] = {'length', 1000, 0, 'mi'},
['mi'] = {'length', 1609.344, 0, 'km'},
['ft'] = {'length', 0.3048, 0, 'm'},
['K'] = {'temperature', 1, 273.15, 'C'},
['C'] = {'temperature', 1, 0, 'F'},
['F'] = {'temperature', 1.8, 32, 'C'},
['°K'] = {'temperature', 1, 273.15, '°C'},
['°C'] = {'temperature', 1, 0, '°F'},
['°F'] = {'temperature', 1.8, 32, '°C'},
}
-------END DATA TABLE-----
local function scaled(value, in_unit, out_unit)
-- Return scaled value for a simple convert.
return (value - in_unit[units.offset]) / in_unit[units.scale] * out_unit[units.scale] + out_unit[units.offset]
end
local function require_number(value, missing, invalid)
-- If value is missing or not a number, throw an error.
-- Return value as a number if valid.
if value == nil then error(missing) end
local number = tonumber(value)
if number == nil then error(invalid:format(value)) end
return number
end
local function require_integer(value, missing, invalid)
-- If value is missing or not an integer, throw an error.
-- Return value as a number if valid.
local number = require_number(value, missing, invalid)
if number ~= math.floor(number) then
error(invalid:format(value))
end
return number
end
local function get_parms(pframe)
-- Return table with all arguments passed by template converted to
-- named arguments. The numeric args are used to add named args:
-- in_text, in_text2 (strings given for value, value2)
-- value, in_unit, out_unit, value2, range, round_to
-- (except for range, which is nil or a table, the named args that are
-- added here could be provided by the user of the template).
local range_types = { -- text to separate input, output ranges
['and'] = {' and ', ' and '},
['by'] = {' by ', ' by '},
['to'] = {' to ', ' to '},
['-'] = {'–', '–'},
['to(-)'] = {' to ', '–'},
['x'] = {' by ', ' × '},
['+/-'] = {' ± ', ' ± '},
}
local args = {} -- arguments passed to template
for k,v in pframe:argumentPairs() do
args[k] = v
end
args.in_text = args[1]
args.value = require_number(args.in_text, 'Need value', 'Value "%s" must be a number')
local in_unit = args[2]
local i = 3
local range = range_types[in_unit]
if range ~= nil then
args.in_text2 = args[3]
args.value2 = require_number(args.in_text2, 'Need second value', 'Second value "%s" must be a number')
in_unit = args[4]
i = 5
end
local out_unit = args[i]
local round_to = args[i+1]
if in_unit == nil then error('Need input unit') end
args.in_unit = in_unit
args.out_unit = out_unit
args.range = range
args.round_to = round_to
return args
end
local function default_roundto(intext, factor)
-- Return a default value for round_to (an integer like 2, 0, -2).
-- prec = (precision implied in intext)
-- = (#digits after dot, or negative of #zeroes before dot)
-- If conversion is multiplication by a factor, and
-- if factor >= 0.02, compensate prec by adding N where:
-- N factor is in range
-- 1 0.02 : 2 = .1/5 : .1*2
-- 0 0.2 : 20 = 1/5 : 1*2
-- -1 2 : 200 = 10/5 : 10*2
-- -2 20 : 2000 = 100/5 : 100*2 etc.
-- Which is achieved with calculation below (log10(5) = 0.69897).
-- TODO Exception required for temperature.
prec = 0
dot = intext:find('.', 1, true)
if dot ~= nil then
prec = intext:sub(dot+1):len()
if prec == 0 then
intext = intext:sub(1, -2)
end
end
if prec == 0 then
prec = -intext:match('0*$'):len()
end
if factor ~= nil and factor >= 0.02 then
prec = prec - math.floor(factor + 0.69897)
end
return prec
end
local function cvtround(invalue, intext, parms)
-- Convert given invalue using parms (return '' if invalue == nil).
-- Return rounded, formatted string for result, using rounding
-- specified in parms.
-- This code combines convert/round because some rounding requires
-- knowledge of what we are converting.
-- TODO Lots of checking required. Will need tweaks for special cases
-- handled by old Template:Convert.
local text = ''
if invalue == nil then return text end
local outvalue = scaled(invalue, parms.in_unit_table, parms.out_unit_table)
local round_to = parms.round_to
local sigfig = parms.sigfig
local disp = parms.disp
local auto = false
if round_to then
-- Ignore sigfig, disp.
round_to = require_integer(round_to, 'Need value', 'round_to "%s" must be an integer')
elseif sigfig then
-- Ignore disp.
sigfig = require_integer(sigfig, 'Need value', 'sigfig "%s" must be an integer')
if sigfig <= 0 then
msg = 'sigfig "%s" must be positive'
error(msg:format(parms.sigfig))
end
local fmt = '%.' .. string.format('%.0f', sigfig) .. 'g'
text = string.format(fmt, outvalue)
elseif disp == '5' then
local negative = false
if outvalue < 0 then
negative = true
outvalue = -outvalue
end
outvalue = math.floor((outvalue / 5) + 0.5) * 5
if negative then
outvalue = -outvalue
end
text = string.format('%.0f', outvalue)
else
auto = true -- using default rounding
-- TODO If conversion is not multiplication by a number, need factor = nil.
local factor = outvalue / invalue
round_to = default_roundto(intext, factor)
end
if round_to then
if auto then
-- TODO: No less than two significant figures.
end
if round_to >= 0 then
local fmt = '%.' .. string.format('%.0f', round_to) .. 'f'
text = string.format(fmt, outvalue)
else
local factor = 10^(-round_to)
local zeroes = string.sub(tostring(factor), 2)
text = string.format('%.0f', outvalue/factor) .. zeroes
end
end
return text
end
local disp_single = {
['or'] = '%s %s or %s %s',
['sqbr'] = '%s %s [%s %s]',
['comma'] = '%s %s, %s %s',
['b'] = '%s %s (%s %s)',
}
local disp_double = {
['or'] = '%s%s%s %s or %s%s%s %s',
['sqbr'] = '%s%s%s %s [%s%s%s %s]',
['comma'] = '%s%s%s %s, %s%s%s %s',
['b'] = '%s%s%s %s (%s%s%s %s)',
}
local function process(parms)
-- If we can convert from given in to out unit, return the table values for the two given unit types.
parms.in_unit_table = units:lookup(parms.in_unit)
if parms.out_unit == nil then -- need to catch empty string also?
parms.out_unit = parms.in_unit_table[units.defaultunit]
end
parms.out_unit_table = units:lookup(parms.out_unit)
if parms.in_unit_table[units.utype] ~= parms.out_unit_table[units.utype] then
local msg = 'Cannot convert %s to %s'
error(msg:format(parms.in_unit_table[units.utype], parms.out_unit_table[units.utype]))
end
local intext = parms.in_text
local intext2 = parms.in_text2
local outext = cvtround(parms.value, intext, parms)
local outext2 = cvtround(parms.value2, intext2, parms)
local range = parms.range
local disp = parms.disp
local wikitext
if range == nil then
wikitext = disp_single[disp] or disp_single['b']
wikitext = wikitext:format(intext, parms.in_unit, outext, parms.out_unit)
else
wikitext = disp_double[disp] or disp_double['b']
wikitext = wikitext:format(intext, range[1], intext2, parms.in_unit, outext, range[2], outext2, parms.out_unit)
end
return wikitext
end
-- Used by template {{convert2}}.
-- We will have to keep old {{convert}} for a long time, and run
-- {{convert2}} in parallel with {{convert}} while testing/developing.
local p = {}
local bodge = require "Module:mw" -- This fixes up mw.text.tag for us.
function p.convert(frame)
local pframe = frame:getParent()
local parms = get_parms(pframe)
local state,text = pcall(process, parms)
if not state then
local params = {style="color:black; background-color:orange;"}
text=mw.text.tag({name="span", contents="[[Module talk:Convert|Conversion error]]: " .. text, params=params})
end
return text
end
return p