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fix bug in color algorithm in an edit (27 August 2015) to Template:Weather box/colt (which this module copied)
make color handling more general so it can process different palettes; include show function to output graphs/table of colors
Line 5: Line 5:
local MINUS = '−' -- Unicode U+2212 MINUS SIGN
local MINUS = '−' -- Unicode U+2212 MINUS SIGN


local function temperature_style(value)
local function temperature_style(palette, value, out_rgb)
-- Return style for a table cell based on the given value which
-- Return style for a table cell based on the given value which
-- should be a temperature in °C.
-- should be a temperature in °C.
local function show(bg, fg)
local function style(bg, fg)
local min, max = unpack(palette.white or { -23, 35 })
if not fg and value and (value < -23.3 or value >= 37.8) then
if not fg and value and (value < min or value >= max) then
fg = 'FFFFFF'
fg = 'FFFFFF'
end
end
Line 20: Line 21:
end
end
if type(value) ~= 'number' then
if type(value) ~= 'number' then
return show('FFFFFF', '000000')
return style('FFFFFF', '000000')
end
end
local red, green, blue
local rgb = out_rgb or {}
for i, v in ipairs(palette) do
if value < -42.75 or value > 60 then
local a, b, c, d = unpack(v)
red = 0
elseif value < 4.47 then
if value <= a then
rgb[i] = 0
red = 5.4 * (42.75 + value)
elseif value > 41.5 then
elseif value < b then
red = 13.78 * (60 - value)
rgb[i] = (value - a) * 255 / (b - a)
elseif value <= c then
else
red = 255
rgb[i] = 255
elseif value < d then
end
if value < -42.75 or value > 41.5 then
rgb[i] = 255 - ( (value - c) * 255 / (d - c) )
else
green = 0
rgb[i] = 0
elseif value < 4.47 then
end
green = 5.4 * (42.75 + value)
elseif value > 4.5 then
green = 6.89 * (41.5 - value)
else
green = 255
end
if value < -90 or value > 23 then
blue = 0
elseif value < -42.78 then
blue = 5.4 * (90 + value)
elseif value > 4.5 then
blue = 13.78 * (23 - value)
else
blue = 255
end
end
return show(string.format('%02X%02X%02X', red, green, blue))
return style(string.format('%02X%02X%02X', rgb[1], rgb[2], rgb[3]))
end
end


local function format_cell(value, intext, outtext)
local function format_cell(palette, value, intext, outtext)
-- Return one line of wikitext to make a cell in a table.
-- Return one line of wikitext to make a cell in a table.
if not value then
if not value then
Line 64: Line 52:
text = intext
text = intext
end
end
return '| ' .. temperature_style(value) .. ' | ' .. text .. '\n'
return '| ' .. temperature_style(palette, value) .. ' | ' .. text .. '\n'
end
end


Line 106: Line 94:
end
end


local function temperature_row(row, inunit, swap)
local function temperature_row(palette, row, inunit, swap)
-- Return 13 lines specifying the style/content of 13 table cells.
-- Return 13 lines specifying the style/content of 13 table cells.
-- Input is 13 space-separated words, each a number (°C or °F).
-- Input is 13 space-separated words, each a number (°C or °F).
Line 125: Line 113:
break
break
end
end
results[n] = format_cell(process_temperature(word, inunit, swap))
results[n] = format_cell(palette, process_temperature(word, inunit, swap))
end
end
for i = n + 1, nrcol do
for i = n + 1, nrcol do
Line 131: Line 119:
end
end
return table.concat(results)
return table.concat(results)
end

local palettes = {
-- A background color entry in a palette is a table of four numbers,
-- say { 11, 22, 33, 44 } (values in °C).
-- That means the color is 0 below 11 and above 44, and is 255 from 22 to 33.
-- The color rises from 0 to 255 between 11 and 22, and falls between 33 and 44.
cool = {
{ -42.75, 4.47, 41.5, 60 },
{ -42.75, 4.47, 4.5, 41.5 },
{ -90 , -42.78, 4.5, 23 },
white = { -23.3, 37.8 },
},
cool2 = {
{ -42.75, 4.5 , 41.5, 56 },
{ -42.75, 4.5 , 4.5, 41.5 },
{ -90 , -42.78, 4.5, 23 },
white = { -23.3, 35 },
},
cool2avg = {
{ -42.75, 4.5 , 33 , 40 },
{ -42.75, 4.5 , 4.5, 33 },
{ -90 , -42.78, 4.5, 23 },
white = { -23.3, 35 },
},
}

local function temperatures(frame, inunit, swap)
local palette = palettes[frame.palette] or palettes.cool
return temperature_row(palette, frame.args[1], inunit, swap)
end
end


local function CtoF(frame)
local function CtoF(frame)
return temperature_row(frame.args[1], 'C')
return temperatures(frame, 'C')
end
end


local function CfromF(frame)
local function CfromF(frame)
return temperature_row(frame.args[1], 'F', true)
return temperatures(frame, 'F', true)
end
end


local function FtoC(frame)
local function FtoC(frame)
return temperature_row(frame.args[1], 'F')
return temperatures(frame, 'F')
end
end


local function FfromC(frame)
local function FfromC(frame)
return temperature_row(frame.args[1], 'C', true)
return temperatures(frame, 'C', true)
end

local chart = [[
{{Graph:Chart
|width=600
|height=180
|xAxisTitle=Celsius
|yAxisTitle=COLOR
|type=line
|x=XVALUES
|y=YVALUES
|colors=COLOR
}}
]]

local function show(frame)
-- For testing, return wikitext to show graphs of how the red/green/blue colors
-- vary with temperature, and a table of the resulting colors.
local function collection()
-- Return a table to hold items.
return {
n = 0,
add = function (self, item)
self.n = self.n + 1
self[self.n] = item
end,
join = function (self, sep)
return table.concat(self, sep)
end,
}
end
local function make_chart(result, color, xvalues, yvalues)
result:add('\n')
local x = xvalues:join(',')
local y = yvalues:join(',')
result:add(frame:preprocess((chart:gsub('COLOR', color):gsub('XVALUES', x):gsub('YVALUES', y))))
end
local palette = palettes[frame.args.palette] or palettes.cool
local data = collection()
local xvals, reds, greens, blues = collection(), collection(), collection(), collection()
local wikitext = collection()
wikitext:add('{| class="wikitable"\n|-\n')
local columns = 0
for celsius = -90, 69 do
local rgb = {}
local style = temperature_style(palette, celsius, rgb)
local R = math.floor(rgb[1])
local G = math.floor(rgb[2])
local B = math.floor(rgb[3])
xvals:add(celsius)
reds:add(R)
greens:add(G)
blues:add(B)
data:add({ celsius, R, G, B })
wikitext:add('| ' .. style .. ' | ' .. celsius .. '\n')
columns = columns + 1
if columns >= 10 then
columns = 0
wikitext:add('|-\n')
end
end
wikitext:add('|}\n')
make_chart(wikitext, 'Red', xvals, reds)
make_chart(wikitext, 'Green', xvals, greens)
make_chart(wikitext, 'Blue', xvals, blues)
return wikitext:join()
end
end


Line 154: Line 238:
FtoC = FtoC,
FtoC = FtoC,
FfromC = FfromC,
FfromC = FfromC,
show = show,
}
}

Revision as of 10:06, 12 September 2016

-- Efficient (fast) functions to implement cells in tables of weather data.
-- Temperature conversion is built-in, but for simplicity, temperatures
-- are assumed to be for habitable locations (from -100 to 100 °C).

local MINUS = '−'  -- Unicode U+2212 MINUS SIGN

local function temperature_style(palette, value, out_rgb)
	-- Return style for a table cell based on the given value which
	-- should be a temperature in °C.
	local function style(bg, fg)
		local min, max = unpack(palette.white or { -23, 35 })
		if not fg and value and (value < min or value >= max) then
			fg = 'FFFFFF'
		end
		if fg then
			fg = 'color:#' .. fg .. ';'
		else
			fg = ''
		end
		return 'style="background:#' .. bg .. ';' .. fg .. ' font-size:85%;"'
	end
	if type(value) ~= 'number' then
		return style('FFFFFF', '000000')
	end
	local rgb = out_rgb or {}
	for i, v in ipairs(palette) do
		local a, b, c, d = unpack(v)
		if value <= a then
			rgb[i] = 0
		elseif value < b then
			rgb[i] = (value - a) * 255 / (b - a)
		elseif value <= c then
			rgb[i] = 255
		elseif value < d then
			rgb[i] = 255 - ( (value - c) * 255 / (d - c) )
		else
			rgb[i] = 0
		end
	end
	return style(string.format('%02X%02X%02X', rgb[1], rgb[2], rgb[3]))
end

local function format_cell(palette, value, intext, outtext)
	-- Return one line of wikitext to make a cell in a table.
	if not value then
		return '|\n'
	end
	local text
	if outtext then
		text = intext .. '<br>(' .. outtext .. ')'
	else
		text = intext
	end
	return '| ' .. temperature_style(palette, value) .. ' | ' .. text .. '\n'
end

local function process_temperature(intext, inunit, swap)
	-- Convert °C to °F or vice versa, assuming the temperature is for a
	-- habitable location, well inside the range -100 to 100 °C.
	-- That simplifies determining precision and formatting (no commas are needed).
	-- Return (celsius_value, intext, outtext) if valid; otherwise return nil.
	-- The returned input and output are swapped if requested.
	-- Each returned string has a Unicode MINUS as sign, if negative.
	local invalue = tonumber(intext)
	if not invalue then return nil end
	local integer, dot, decimals = intext:match('^%s*%-?(%d+)(%.?)(%d*)%s*$')
	if not integer then return nil end
	if invalue < 0 then
		intext = MINUS .. integer .. dot .. decimals
	end
	local outtext
	if inunit == 'C' or inunit == 'F' then
		local celsius_value, outvalue
		if inunit == 'C' then
			outvalue = invalue * (9/5) + 32
			celsius_value = invalue
		else
			outvalue = (invalue - 32) * (5/9)
			celsius_value = outvalue
		end
		local precision = dot == '' and 0 or #decimals
		outtext = string.format('%.' .. precision .. 'f', math.abs(outvalue) + 2e-14)
		if outvalue < 0 and tonumber(outtext) ~= 0 then
			-- Don't show minus if result is negative but rounds to zero.
			outtext = MINUS .. outtext
		end
		if swap then
			return celsius_value, outtext, intext
		end
		return celsius_value, intext, outtext
	end
	-- LATER Think about whether a no-conversion option would be useful.
	return invalue, intext, outtext
end

local function temperature_row(palette, row, inunit, swap)
	-- Return 13 lines specifying the style/content of 13 table cells.
	-- Input is 13 space-separated words, each a number (°C or °F).
	-- Any word that is not a number gives a blank cell ("M" for a missing cell).
	-- Any excess words are ignored.
	--
	-- Function  Input   Output
	-- ------------------------
	-- CtoF        C       C/F
	-- FfromC      C       F/C
	-- CfromF      F       C/F
	-- FtoC        F       F/C
	local nrcol = 13
	local results, n = {}, 0
	for word in row:gmatch('%S+') do
		n = n + 1
		if n > nrcol then
			break
		end
		results[n] = format_cell(palette, process_temperature(word, inunit, swap))
	end
	for i = n + 1, nrcol do
		results[i] = format_cell()
	end
	return table.concat(results)
end

local palettes = {
	-- A background color entry in a palette is a table of four numbers,
	-- say { 11, 22, 33, 44 } (values in °C).
	-- That means the color is 0 below 11 and above 44, and is 255 from 22 to 33.
	-- The color rises from 0 to 255 between 11 and 22, and falls between 33 and 44.
	cool = {
		{ -42.75,   4.47, 41.5, 60   },
		{ -42.75,   4.47,  4.5, 41.5 },
		{ -90   , -42.78,  4.5, 23   },
		white = { -23.3, 37.8 },
	},
	cool2 = {
		{ -42.75,   4.5 , 41.5, 56   },
		{ -42.75,   4.5 ,  4.5, 41.5 },
		{ -90   , -42.78,  4.5, 23   },
		white = { -23.3, 35 },
	},
	cool2avg = {
		{ -42.75,   4.5 , 33  , 40   },
		{ -42.75,   4.5 ,  4.5, 33   },
		{ -90   , -42.78,  4.5, 23   },
		white = { -23.3, 35 },
	},
}

local function temperatures(frame, inunit, swap)
	local palette = palettes[frame.palette] or palettes.cool
	return temperature_row(palette, frame.args[1], inunit, swap)
end

local function CtoF(frame)
	return temperatures(frame, 'C')
end

local function CfromF(frame)
	return temperatures(frame, 'F', true)
end

local function FtoC(frame)
	return temperatures(frame, 'F')
end

local function FfromC(frame)
	return temperatures(frame, 'C', true)
end

local chart = [[
{{Graph:Chart
|width=600
|height=180
|xAxisTitle=Celsius
|yAxisTitle=COLOR
|type=line
|x=XVALUES
|y=YVALUES
|colors=COLOR
}}
]]

local function show(frame)
	-- For testing, return wikitext to show graphs of how the red/green/blue colors
	-- vary with temperature, and a table of the resulting colors.
	local function collection()
		-- Return a table to hold items.
		return {
			n = 0,
			add = function (self, item)
				self.n = self.n + 1
				self[self.n] = item
			end,
			join = function (self, sep)
				return table.concat(self, sep)
			end,
		}
	end
	local function make_chart(result, color, xvalues, yvalues)
		result:add('\n')
		local x = xvalues:join(',')
		local y = yvalues:join(',')
		result:add(frame:preprocess((chart:gsub('COLOR', color):gsub('XVALUES', x):gsub('YVALUES', y))))
	end
	local palette = palettes[frame.args.palette] or palettes.cool
	local data = collection()
	local xvals, reds, greens, blues = collection(), collection(), collection(), collection()
	local wikitext = collection()
	wikitext:add('{| class="wikitable"\n|-\n')
	local columns = 0
	for celsius = -90, 69 do
		local rgb = {}
		local style = temperature_style(palette, celsius, rgb)
		local R = math.floor(rgb[1])
		local G = math.floor(rgb[2])
		local B = math.floor(rgb[3])
		xvals:add(celsius)
		reds:add(R)
		greens:add(G)
		blues:add(B)
		data:add({ celsius, R, G, B })
		wikitext:add('| ' .. style .. ' | ' .. celsius .. '\n')
		columns = columns + 1
		if columns >= 10 then
			columns = 0
			wikitext:add('|-\n')
		end
	end
	wikitext:add('|}\n')
	make_chart(wikitext, 'Red', xvals, reds)
	make_chart(wikitext, 'Green', xvals, greens)
	make_chart(wikitext, 'Blue', xvals, blues)
	return wikitext:join()
end

return {
	CtoF = CtoF,
	CfromF = CfromF,
	FtoC = FtoC,
	FfromC = FfromC,
	show = show,
}
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