I found a Python script that I'm trying to convert to Lua. I believe I have it just about converted, but the code isn't quite working properly, so I need assistance as I do not know Python at all, and can only guess at the intentions. This is merely a color converter to convert RGB color to xterm 256. The table is quite huge, so I've truncated it for ease of reading.
Python code:
import sys, re
CLUT = [ # color look-up table
# 8-bit, RGB hex
# Primary 3-bit (8 colors). Unique representation!
('00', '000000'),
('01', '800000'),
('02', '008000'),
('03', '808000'),
('04', '000080'),
('05', '800080'),
('06', '008080'),
('07', 'c0c0c0'),
]
def _str2hex(hexstr):
return int(hexstr, 16)
def _strip_hash(rgb):
# Strip leading `#` if exists.
if rgb.startswith('#'):
rgb = rgb.lstrip('#')
return rgb
def _create_dicts():
short2rgb_dict = dict(CLUT)
rgb2short_dict = {}
for k, v in short2rgb_dict.items():
rgb2short_dict[v] = k
return rgb2short_dict, short2rgb_dict
def short2rgb(short):
return SHORT2RGB_DICT[short]
def print_all():
""" Print all 256 xterm color codes.
"""
for short, rgb in CLUT:
sys.stdout.write('\033[48;5;%sm%s:%s' % (short, short, rgb))
sys.stdout.write("\033[0m ")
sys.stdout.write('\033[38;5;%sm%s:%s' % (short, short, rgb))
sys.stdout.write("\033[0m\n")
print "Printed all codes."
print "You can translate a hex or 0-255 code by providing an argument."
def rgb2short(rgb):
""" Find the closest xterm-256 approximation to the given RGB value.
@param rgb: Hex code representing an RGB value, eg, 'abcdef'
@returns: String between 0 and 255, compatible with xterm.
>>> rgb2short('123456')
('23', '005f5f')
>>> rgb2short('ffffff')
('231', 'ffffff')
>>> rgb2short('0DADD6') # vimeo logo
('38', '00afd7')
"""
rgb = _strip_hash(rgb)
incs = (0x00, 0x5f, 0x87, 0xaf, 0xd7, 0xff)
# Break 6-char RGB code into 3 integer vals.
parts = [ int(h, 16) for h in re.split(r'(..)(..)(..)', rgb)[1:4] ]
res = []
for part in parts:
i = 0
while i < len(incs)-1:
s, b = incs[i], incs[i+1] # smaller, bigger
if s <= part <= b:
s1 = abs(s - part)
b1 = abs(b - part)
if s1 < b1: closest = s
else: closest = b
res.append(closest)
break
i += 1
#print '***', res
res = ''.join([ ('%02.x' % i) for i in res ])
equiv = RGB2SHORT_DICT[ res ]
#print '***', res, equiv
return equiv, res
RGB2SHORT_DICT, SHORT2RGB_DICT = _create_dicts()
#---------------------------------------------------------------------
if __name__ == '__main__':
import doctest
doctest.testmod()
if len(sys.argv) == 1:
print_all()
raise SystemExit
arg = sys.argv[1]
if len(arg) < 4 and int(arg) < 256:
rgb = short2rgb(arg)
sys.stdout.write('xterm color \033[38;5;%sm%s\033[0m -> RGB exact \033[38;5;%sm%s\033[0m' % (arg, arg, arg, rgb))
sys.stdout.write("\033[0m\n")
else:
short, rgb = rgb2short(arg)
sys.stdout.write('RGB %s -> xterm color approx \033[38;5;%sm%s (%s)' % (arg, short, short, rgb))
sys.stdout.write("\033[0m\n")
And my nearly complete translated Lua code:
CLUT = {
-- Primary 3-bit (8 colors). Unique representation!
['00'] = '000000',
['01'] = '800000',
['02'] = '008000',
['03'] = '808000',
['04'] = '000080',
['05'] = '800080',
['06'] = '008080',
['07'] = 'c0c0c0',
}
function _str2hex(hexstr)
return tonumber(hexstr, 16)
end
function _strip_hash(rgb)
-- Strip leading # if exists
return rgb:gsub("^#", "")
end
function _create_dicts()
short2rgb_dict = CLUT
rgb2short_dict = {}
for k,v in pairs(short2rgb_dict) do
rgb2short_dict[v] = k
end
return rgb2short_dict, short2rgb_dict
end
function short2rgb(short)
return short2rgb_dict[short]
end
function rgb2short(rgb)
-- Find closest xterm-256 approximation to the given RGB value
_create_dicts()
rgb = _strip_hash(rgb)
local res = ""
local equiv = ""
local incs = {"0x00", "0x5f", "0x87", "0xaf", "0xd7", "0xff"}
for part in string.gmatch(rgb, "(..)") do
part = tonumber(part, 16)
i = 1
while i < #incs - 1 do
s, b = tonumber(incs[i]), tonumber(incs[i+1])
if s <= part and part <= b then
s1 = math.abs(s - part)
b1 = math.abs(b - part)
end
if s1 < b1 then
closest = s
else
closest = b
res = res .. closest
break
end
i = i + 1
end
end
equiv = rgb2short_dict[res]
return equiv, res
end
I realize that I'm missing the printing portion of the code, but I wasn't sure if that was at all relevant, and I know some of the code I've translated is not correct at all, as the script would be working otherwise. The failures I get are with the rgb2short function with it not returning the proper equiv and res values. How far off am I with my revision? What changes do I need to make to make it absolutely work?
I wound up figuring it out on my own after some hardcore trial and error. The function rgb2short should have been:
function rgb2short(rgb)
-- Find closest xterm-256 approximation to the given RGB value
_create_dicts()
rgb = _strip_hash(rgb)
local res = ""
local equiv = ""
local incs = {"0x00", "0x5f", "0x87", "0xaf", "0xd7", "0xff"}
for part in string.gmatch(rgb, "(..)") do
part = tonumber(part, 16)
i = 1
while i < #incs-1 do
s, b = tonumber(incs[i]), tonumber(incs[i+1])
if s <= part and part <= b then
s1 = math.abs(s - part)
b1 = math.abs(b - part)
--break
--end
if s1 < b1 then
closest = s
else
closest = b
end
res = res .. string.format("%02x", closest)
break
end
i = i + 1
end
end
equiv = rgb2short_dict[res]
return equiv, res
end