Remove specific entry from Lua table - lua

I am inserting into a table like this
Admin = {}
table.insert(Admins, {id = playerId, Count = 0})
And that works fine.
How do I remove that specific admin from that table now?
The following does not work, and Im sure its because ID is stored in an array that's inside of the table, but how would I access that then?
table.remove(Admins, playerId)
Basically,
I want to remove from the table Admins, where the ID == playerId that I input.

There are two approaches to remove an entry from the table, both are acceptable ways:
1. myTable[index] = nil Removes an entry from given index, but adds a hole in the table by maintaining the indices
local Admins = {}
table.insert(Admins, {id = 10, Count = 0})
table.insert(Admins, {id = 20, Count = 1})
table.insert(Admins, {id = 30, Count = 2})
table.insert(Admins, {id = 40, Count = 3})
local function removebyKey(tab, val)
for i, v in ipairs (tab) do
if (v.id == val) then
tab[i] = nil
end
end
end
-- Before
-- [1] = {['Count'] = 0, ['id'] = 10},
-- [2] = {['Count'] = 1, ['id'] = 20},
-- [3] = {['Count'] = 2, ['id'] = 30},
-- [4] = {['Count'] = 3, ['id'] = 40}}
removebyKey(Admins, 20)
-- After
-- [1] = {['Count'] = 0, ['id'] = 10},
-- [3] = {['Count'] = 2, ['id'] = 30},
-- [4] = {['Count'] = 3, ['id'] = 40}
2. table.remove(myTable, index)
Removes the entry from given index and renumbering the indices
local function getIndex(tab, val)
local index = nil
for i, v in ipairs (tab) do
if (v.id == val) then
index = i
end
end
return index
end
local idx = getIndex(Admins, 20) -- id = 20 found at idx = 2
if idx == nil then
print("Key does not exist")
else
table.remove(Admins, idx) -- remove Table[2] and shift remaining entries
end
-- Before is same as above
-- After entry is removed. Table indices are changed
-- [1] = {['id'] = 10, ['Count'] = 0},
-- [2] = {['id'] = 30, ['Count'] = 2},
-- [3] = {['id'] = 40, ['Count'] = 3}

Related

Get all repeated itens from a table in Lua

I need a little help here
Let's suppose I have a table with numbers.
tbl = {'item1' = 6, 'item2' = 1, 'item3' = 6, 'item4' = 3, 'item5' = 2, 'item5' = 3}
I wanna put all repeated numbers in the same table (with key and value) like this:
repeated = {'item1' = 6, 'item3' = 6, 'item4' = 3, 'item5' = 3}
and creat a new one with the "not repeated" numbers:
notrepeated = {'item2' = 1, 'item5' = 2}
Can someone help? Thank you so much.
-- Count the items for each number
local itemsByNum = {}
for item, num in pairs(tbl) do
itemsByNum[num] = (itemsByNum[num] or 0) + 1
end
-- Now move objects to the respective tables
local rep, noRep = {}, {} -- can't use "repeat" as that's a Lua keyword
for item, num in pairs(tbl) do
if itemsByNum[num] > 1 then -- repeated at least once
rep[item] = num
else -- unique number
norep[item] = num
end
end

How to update/reload table key values

How can i update a key value using another key value as variable which is inside the same table?
local t = {}
t.playerPosition = {x = 0, y = 0, z = 0}
t.positions = {t.playerPosition.x + 1, t.playerPosition.y + 1, t.playerPosition.z + 1}
Then few lines later i update playerPosition
t.playerPosition = {x = 125, y = 50, z = 7}
And then if i print out...
result
t.positions[1] -- outputs 1
t.positions[2] -- outputs 1
t.positions[3] -- outputs 1
expected result
t.positions[1] -- outputs 126
t.positions[2] -- outputs 51
t.positions[3] -- outputs 8
As you can see key positions isnt updating, what could i do to make it possible?
t.positions = {t.playerPosition.x + 1, t.playerPosition.y + 1, t.playerPosition.z + 1}
In the above line, the expressions are evaluated once, and the resulting values are assigned to fields of the subtable. After this point, changes to the fields of t.playerPosition will not cause a reflected change in t.positions.
Metatables can be used to enable such behaviour, by dynamically calculating results when accessing the fields of t.positions.
local t = {}
t.playerPosition = { x = 0, y = 0, z = 0 }
t.positions = setmetatable({}, {
__newindex = function () return false end,
__index = function (_, index)
local lookup = { 'x', 'y', 'z' }
local value = t.playerPosition[lookup[index]]
if value then
return value + 1
end
end
})
print(t.positions[1], t.positions[2], t.positions[3])
t.playerPosition = {x = 125, y = 50, z = 7}
print(t.positions[1], t.positions[2], t.positions[3])

Most optimized way to get value from table

I need to check if first value is >= 'from' and second value is <= 'to', if true then my function retun number. It's working but I don't know if this is the best and most optimized way to get value(number from table).
local table = {
{from = -1, to = 12483, number = 0},
{from = 12484, to = 31211, number = 1},
{from = 31212, to = 53057, number = 2},
{from = 53058, to = 90200, number = 3},
{from = 90201, to = 153341, number = 4},
{from = 153342, to = 443162, number = 5},
{from = 443163, to = 753380, number = 6},
{from = 753381, to = 1280747, number = 7},
{from = 1280748, to = 2689570, number = 8},
{from = 2689571, to = 6723927, number = 9},
{from = 6723928, to = 6723928, number = 10}
}
local exampleFromValue = 31244
local exampleToValue = 42057
local function getNumber()
local number = 0
for k, v in pairs(table) do
if (v.from and exampleFromValue >= v.from) and (v.to and exampleToValue <= v.to) then
number = v.number
break
end
end
return number
end
print(getNumber())
With this small amount of data, such function doesn't seem like a performace issue. However, you can compress the data a bit:
local t = {
12484, 31212, 53058, 90201, 153342, 443163, 753381, 1280748, 2689571, 6723928
}
local exampleFromValue = 31244
local exampleToValue = 42057
local function getNumber()
local last = -1
for i, v in ipairs(t) do
if exampleFromValue >= last and exampleToValue < v then
return i - 1
end
last = v
end
return 0
end

Find the nearest value

I'm looking for a way to find out which value is closest to x in a table and return that.
Lets assume, for a second, X is x=15, we have the table with 4 values {12, 190, 1, 18}, How do I make it so in this case the first key&value is returned?
x = 15
table = {190, 1, 12, 18}
function NearestValue(table, number)
local smallestSoFar, smallestIndex
for i, y in ipairs(table) do
if not smallestSoFar or (math.abs(number-y) < smallestSoFar) then
smallestSoFar = math.abs(number-y)
smallestIndex = i
end
end
return smallestIndex, table[smallestIndex]
end
index, value = NearestValue(table,x)
print(index)
print(value)
I would do something like this:
initialdiff = 1000000000000
selectedkey = -1
values = {12, 190, 1, 18}
x = 15
for key, val in pairs (values) do
currentdiff = math.fabs(val - x)
if (currentdiff < initialdiff) do
initialdiff = currentdiff
selectedkey = key
end
end
-- selectedkey now holds key for closest match
-- values[selectedkey] gives you the (first) closest value

Mean/median/mode from complex table in lua

Thank you for all the support with lua, I'm very new and my application is working nicely so far.
I've made an app that will take in a few thousand numbers for different items. I'm trying to find the Mean/Media/Mode for each item, I've been able to do this for a single item, but not for all items.
Here is my table structure:
for i = 0, 1500 do
local e = {}
e.seller,
e.buyer,
e.itemName,
e.soldAmount = GetSoldAmount(FromMember(i))
table.insert(allSalesTempTable, e)
end
Table output format
[1] =
{
["itemName"] = [[Salad]]
["buyer"] = [[#Mike]],
["eventType"] = 15,
["soldAmount"] = 150,
["seller"] = [[#Sarah]],
},
[2] =
{
["itemName"] = [Pizza]
["buyer"] = [[#James]],
["eventType"] = 15,
["soldAmount"] = 150,
["seller"] = [[#Sarah]],
},
[3] =
{
["itemName"] = [Salad]
["buyer"] = [[#Frank]],
["eventType"] = 15,
["soldAmount"] = 75,
["seller"] = [[#Sarah]],
},
[4] ...
},
Then I'm trying to send the table/array to this mean function
stats={}
-- Get the mean value of a table
function stats.mean( t )
local sum = 0
local count= 0
local tempTbl = {}
(This is completely not going to work, but its what I'm trying so far)
for k,v in pairs(t) do tempTbl[k] = v
if v.itemName == tempTbl.itemName then
sum = sum + v.soldAmount
count = count + 1
end
end
return (sum / count)
end
--- To get the function started
stats.mean(e)
Here is where I'm getting fuzzy, Not sure if I can add the MEAN while collecting the data into the first temp table, or if it needs to be re-calculated after I have all the data?
If it needs to be done after, then my stats.mean(e) needs a way to insert it?
I'm trying to get this output:
[1] =
{
["itemName"] = [[Salad]]
["buyer"] = [[#Mike]],
["eventType"] = 15,
["soldAmount"] = 150,
["seller"] = [[#Sarah]],
["mean"] = 112.5 - New Insert somehow
},
[2] =
{
["itemName"] = [Pizza]
["buyer"] = [[#James]],
["eventType"] = 15,
["soldAmount"] = 150,
["seller"] = [[#Sarah]],
["mean"] = 150 - New Insert somehow
},
[3] =
{
["itemName"] = [Salad]
["buyer"] = [[#Frank]],
["eventType"] = 15,
["soldAmount"] = 75,
["seller"] = [[#Sarah]],
["mean"] = 112.5 - New Insert somehow
},
[4] ...
},
I've been working on this problem for a few days, After I see how to adjust my format for the mean and insert into the existing table I'll be able to figure out mean/min/max/median/mode easy enough.

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