Sorry to bother anyone…I’m trying to get to grips with Lua basic functions. And have written the following code which works exactly as I want it to, however as I’m on steep learning curve I would be grateful to know if there is a much simpler way of achieving the aims of the code, or if the code itself could be more elegantly formed.
--to convert the numbers 0 to 255 into binary
--and store the binary code for each number in a table.
function setup()
maptilecode={} -- creates table/array
for ident = 1,256 do
maptilecode[ident]={} -- makes 256 columns long
for y=1,9 do
maptilecode[ident][y]=0 -- by 9 rows deep, all entries 0
end
binary(ident,ident-1,1) -- now writes the binary code for the value,
-- 1 less than the identity to the
-- identity col in maptile code
end
end
function binary(ident,rntot,i) -- fnc "binary" recieves identity,
-- initial running total and counter
rntot,r=math.modf(rntot/2) -- gives int and float on division by 2
if r>0 then r=1 else r=0 end -- converts float to binary remainder
maptilecode[ident][i]=r -- records remainder as digit in maptilecode
i = i + 1 -- increases count
if rntot>0 then binary(ident,rntot,i) else return -- again or stop?
end
end
Also as you may have noticed I haven’t understood how to paste code in properly so that it maintains all it’s colours etc. Any advice would be nice. Sorry I’m a complete novice.
It looks like you are converting to binary, this should do the trick:
function setup()
maptilecode={} -- creates table/array
for ident = 1,256 do
maptilecode[ident]=toBinary(ident, 9) -- makes 256 columns long
end
end
function toBinary(n, b) -- number, amount of bits used
local t = {}
for i = b - 1, 0, -1 do
local e = 2 ^ i
if n >= e then
n = n - e
table.insert(t, 1)
else
table.insert(t, 0)
end
end
return t
end
Personally, no offence @Jordan but I think this is a better method
function setup()
bin = {}
for i = 1, 256 do
table.insert(bin, decToBase(i-1, 2))
print(bin[i])
end
end
function decToBase(IN, BASE)
local B,K,OUT,D = BASE or 10, "0123456789ABCDEFGHIJKLMNOPQRSTUVW", ""
if IN > 0 then
while IN>0 do
IN, D = math.floor(IN/B), math.mod(IN,B)+1
OUT = string.sub(K,D,D)..OUT
end
else
OUT = 0
end
return OUT
end
not only can it convert to binary, it can also convert to other bases as base 8 and 16
Note that I didn’t write this myself, I did a little research
None Taken, all in the name of elegant coding. I saw that page too :), but I thought that because the original post dealt with binary it would be faster to do pure binary math.
This is somewhat unrelated… But it’s pretty difficult to write clean code for Codea anyways, because there’s no proper concept of a namespace. The global namespace just gets cluttered with more and more stuff.
Also: what idiot when designing lua decided that all variables should be global by default? I can just about tolerate duck typing and the other stuff, but that was just pure evil.
Here’s another way to create a binary table for the numbers 0 to 255.
function setup()
binTab={}
for z=0,255 do
bin(z)
end
print(table.concat(binTab,"\
"))
end
function bin(z)
str=""
for a=7,0,-1 do
if z>=2^a then
str=str.."1"
z=z-2^a
else
str=str.."0"
end
end
table.insert(binTab,str)
end
