can I simplify this for loop?

MoKaLux · September 2019

I have a question please. Can I simplify this for loop?

	local map = {}
	for line in io.lines("map1.txt") do
		map[#map + 1] = line
	end
 
	local mapid = {}
	for r = 1, #map do
		mapid[r] = {}
		for c = 1, #map[r] do
			mapid[r][#mapid[r] + 1] = "x"
		end
	end

I try to use only one table instead of two. Is this possible? Thank you for your time.

talis · September 2019

I am not an expert in Lua code optimizations but found a good article, and start to read when i saw your post. So many good suggestions exist, have a look. Maybe it will not help in this specific question but in general you will gain favor of it.
https://www.lua.org/gems/sample.pdf

MoKaLux · September 2019

thank you very much @talis

Rule #1:Don’t do it.
Rule #2:Don’t do it yet.(for experts only)

I am trying to optimize my code but sometimes I complicate it more!
For my problem I simply do:

	local map = {}
	for line in io.lines("map1.txt") do
		map[#map + 1] = line
	end
 
	for r = 1, #map do
		for c = 1, #map[r] do
			local id = string.sub(map[r], c, c + x - 1)
		end
	end

Once again thank you!

Apollo14 · September 2019

If we talk about optimization-masturbation, it's bad practice to use '#' (as well as 'table.insert', cause this way lua recalculates array size every time).

--"Bad":
local map = {}
for line in io.lines("map1.txt") do
	map[#map + 1] = line
end
 
--"Good":
local map = {}
local mapArrSize=1
for line in io.lines("map1.txt") do
	map[mapArrSize] = line
	mapArrSize+=1
end

I'm too sleepy now to suggest anything wise

MoKaLux · September 2019

thank you @Apollo14 I will change my code to reflect your optimization.
BTW: my initial purpose was not to optimize but to simplify my loops because it seemed to me that those two loops could be merged into one, but I was wrong. I still have a lot to learn regarding lua and gideros.

Apollo14 · September 2019

Take a pil every day!

https://www.lua.org/pil/contents.html

(I stopped taking them somewhere in the middle

but I feel like I should continue my treatment)

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