## Mini Functions Repository

General discussion about LÖVE, Lua, game development, puns, and unicorns.
Positive07
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Posts: 1006
Joined: Sun Aug 12, 2012 4:34 pm
Location: Argentina

### Re: Mini Functions Repository

HugoBDesigner wrote:I wrote a simple array organizer for numerical entries. I know these things come with Lua already, but after I wrote one for strings (long ago, dunno where to find it), I figured I'd give numbers a try:
Mmm sorry but wouldn't [manual]table.sort[/manual] work?
for i, person in ipairs(everybody) do
[tab]if not person.obey then person:setObey(true) end
end
love.system.openURL(Github.com/Positive07)

HugoBDesigner
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### Re: Mini Functions Repository

Yeah, it would, but it was mostly experimental. I already knew of table.sort, but figured I'd give it a try to see how it'd work.
Speaking of that, I finally found the alphabetical organizer: it was in my Minigame Simulator all along

Code: Select all

function alphabetic_order(a, b)
local g = "abcdefghijklmnopqrstuvwxyz"
local alphabet = {}
for i = 1, string.len(g) do table.insert(alphabet, string.sub(g, i, i)) end

local a, b = string.lower(a), string.lower(b)
for j = 1, math.min(string.len(a), string.len(b)) do
local aa, bb = string.sub(a, j, j), string.sub(b, j, j)
if aa ~= bb then
if table.contains(alphabet, aa) and table.contains(alphabet, bb) then
if table.contains(alphabet, aa) < table.contains(alphabet, bb) then
return true
elseif table.contains(alphabet, aa) > table.contains(alphabet, bb) then
return false
end
elseif table.contains(alphabet, aa) then
return false
else
return true
end
elseif j == math.min(string.len(a), string.len(b)) then --virtually similar, return the smallest as first
return (string.len(a) < string.len(b) and true) or false
end
end
end

And to use it:

Code: Select all

table.sort(table, function(a, b)
return alphabetic_order(table[a], table[b])
end)

HugoBDesigner - my Blog

Positive07
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Posts: 1006
Joined: Sun Aug 12, 2012 4:34 pm
Location: Argentina

### Re: Mini Functions Repository

You can take this part out of the function since it is constant:

Code: Select all

   local g = "abcdefghijklmnopqrstuvwxyz"
local alphabet = {}
for i = 1, string.len(g) do table.insert(alphabet, string.sub(g, i, i)) end

Then again, you can compare two strings in Lua with > and < and they sort alphabetically, not sure about caps but you can always do

Code: Select all

table.sort(t, function (a, b)
return string.lower(a) < string.lower(b)
end)

for i, person in ipairs(everybody) do
[tab]if not person.obey then person:setObey(true) end
end
love.system.openURL(Github.com/Positive07)

davisdude
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Posts: 1154
Joined: Sun Apr 28, 2013 3:29 am
Location: North Carolina

### Re: Mini Functions Repository

How 'bout this?

Code: Select all

function alphabetic_sort(a,b)
-- Handle words that are the same until a certain point
local i = 1
while a:sub( i, i ) == b:sub( i, i ) do
i = i + 1
-- No letter goes before words with letters
if i > #a then return true end
if i > #b then return false end
end
return a:sub( i, i ) < b:sub( i, i )
end
Use it in the same way:

Code: Select all

table.sort( tab, alphabetic_sort )
-- Reverse alphabetized
table.sort( tab, function( a, b ) return not alphabetic_sort( a, b ) end )
Plus, it doesn't rely on table.contains

*edit: Thanks to Positive07 for teaching me you can compare strings with '<' and '>'!
GitHub | MLib - Math and shape intersections library | Walt - Animation library | Brady - Camera library with parallax scrolling | Vim-love-docs - Help files and syntax coloring for Vim

Positive07
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Posts: 1006
Joined: Sun Aug 12, 2012 4:34 pm
Location: Argentina

### Re: Mini Functions Repository

I'm pretty sure you can do that just with table.sort:

Code: Select all

local t = {
"something",
"somewhere",
"someone",
"someday",
"some",
"so",
"s",
"abc"
}

table.sort(t)

for i, v in ipairs(t) do
print(i, v)
end

--Output:
--1	abc
--2	s
--3	so
--4	some
--5	someday
--6	someone
--7	something
--8	somewhere

Note, uppercase are sorted first and then lower case, that is "S" is lower than "s" so if you need to ignore case then use the code I posted before:

Code: Select all

table.sort(t, function (a,b) return string.lower(a) < string.lower(b) end)

for i, person in ipairs(everybody) do
[tab]if not person.obey then person:setObey(true) end
end
love.system.openURL(Github.com/Positive07)

zorg
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Location: Absurdistan, Hungary
Contact:

### Re: Mini Functions Repository

String sorting probably follows the underlying encoding's numerical values, and since the first 127 should be somewhat standard across all "ansi" codepages (or, if you want me to be utterly explicit, will be equivalent to ISO/IEC_8859-1 and/or Windows-1252), the order of 0-9A-Za-z will be adhered to. Don't quote me on this though.
Me and my stuff True Neutral Aspirant. Why, yes, i do indeed enjoy sarcastically correcting others when they make the most blatant of spelling mistakes. No bullying or trolling the innocent tho.

Positive07
Party member
Posts: 1006
Joined: Sun Aug 12, 2012 4:34 pm
Location: Argentina

### Re: Mini Functions Repository

I quote you on that, that is how it works, and it does it on a character by character basics, so if the first is equal it goes with the next one and so on...
for i, person in ipairs(everybody) do
[tab]if not person.obey then person:setObey(true) end
end
love.system.openURL(Github.com/Positive07)

pgimeno
Party member
Posts: 2020
Joined: Sun Oct 18, 2015 2:58 pm

### Re: Mini Functions Repository

Here's a pair of functions that allow storing tuples into tables and then retrieving back these tables as tuples:

Code: Select all

local function pack_n(...)
return {select('#', ...), ...}
end

local unpack_n
do
local function unpack_count(x, n)
if n == x[1] + 1 then
return
end
n = n + 1
return x[n], unpack_count(x, n)
end

function unpack_n(a)
return unpack_count(a, 1)
end
end

Example usage:

Code: Select all

local function my_crazy_func()
return nil, 2, 3, nil, "yes", math.acos(3), false, nil
end

-- Store the returned tuple in a table
local packed = pack_n(my_crazy_func())
-- Retrieve the table as a tuple and print it
print(unpack_n(packed))
-- output: nil	2	3	nil	yes	nan	false	nil

-- By comparison, using the default Lua unpack fails with the nils:
packed = {my_crazy_func()}
print(unpack(packed))
-- output: nil 2 3


ReFreezed
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Location: Sweden
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### Re: Mini Functions Repository

pgimeno wrote:
Mon Mar 02, 2020 10:44 am
Here's a pair of functions that allow storing tuples into tables and then retrieving back these tables as tuples:
Lua 5.2 adds a similar "pack" function to the standard table module that's implemented like this:

Code: Select all

local function pack(...)
return {n=select("#", ...), ...}
end
local function getSomeValues()
return 8, nil, "foo"
end
local packed = pack(getSomeValues())
print(unpack(packed, 1, packed.n)) -- 8 nil foo

I wanna say it's a more "standard" way of storing and using tuples (not that it really matters for such a simple little thing ).