Maybe I'm missing a keyword in my searches for a solution, but I didn't find what I'm looking for.
In Google Sheets I want to take a set of numbers and reorder it randomly. For example, start with the set [1,2,3,4] and get back [4,2,1,3].
Any ideas which function or a combination of functions may achieve this goal?
The entire process that I want to achieve is something like this:
I have a set of 4 fields. Their sum is fixed. I want to assign them randomized values.
So, I was thinking to iterate through this process:
Create a random integer between 0 and the max possible value (in the first iteration it's the fixed sum)
The new max value is the last max value minus the new random number.
Check if the new max is zero.
If not:
Return to the 1st step and repeat - This goes on until there are four values
If needed the 4th value shall be increased so the total will match the fixed sum.
Else, continue.
Randomize the order of the 4 values.
Assign the values to the 4 fields.
try:
=INDEX(SORT({{1; 2; 3; 4}, RANDARRAY(4, 1)}, 2, ),, 1)
or:
=INDEX(SORT({ROW(1:4), RANDARRAY(4, 1)}, 2, ),, 1)
Here are a couple of app script examples as well
function DiceRolls(nNumRolls) {
var anRolls = [];
nNumRolls = DefaultTo(nNumRolls, 1000)
for (var i = 1;i <= nNumRolls; i++) {
anRolls.push(parseInt((Math.random() * 6))+1);
}
return anRolls;
}
function CoinFlips(nNumFlips) {
var anFlips = [];
nNumFlips = DefaultTo(nNumFlips, 1000)
for (var i = 1;i <= nNumFlips; i++) {
anFlips.push(getRndInteger(1,2));
}
return anFlips;
}
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min + 1) ) + min;
}
I wanted to make a madden mobile sniping bot. So I wanted to use the findImage function to find if a player has sold or not. Here is what I'm thinking.
The first image would be my screen and the second image would be what image I'm trying to find, and if it find it it will tap on it. Here is my script:
local r = findImage ( "/images/auction.bmp" ,1, 1, nil, nil);
if r == nil then alert ( "nil" );
else local n = 0;
for i, v in pairs (r) do n = n + 1;
end if n == 0 then alert ( "false" );
else
alert ( "true" );
end
end
It runs but always returns false. So I was wondering if I'm using the findImage function right and if so why doesn't it return true?
The end statement at line 5 closes the for loop and is directly followed by another if statement before the first one at line 2 has been closed.
Try ending both before issuing another condition.
I'd also recommend lowering the finding tolerance a little. A value of 1 is the most strict which means every single pixel must match precisely in order to be found. A value of 0.8 is just as accurate when finding such a large image yet still allows some fuzziness for improving detection.
Something like this should work.
local r = findImage ( "/images/auction.bmp" ,1, 0.8, nil, nil);
local n = 0;
if r == nil then alert ( "nil" ); else
for i, v in pairs (r) do n = n + 1;
end
end
if n == 0 then alert ( "false" );
else alert ( "true" );
end
I have a c function that is called from lua. The first parameter is a table. That table is abused as an input array of numbers to an underlying api. So right now my code looks like this:
int n = 0;
lua_pushnil ( L );
while ( lua_next ( L, 2 ) ) {
n++;
lua_pop ( L, 1 );
}
int *flat = alloca ( n * 4 );
lua_pushnil ( L );
int i = 0;
while ( lua_next(L,2) ) {
flat[i++] = (int)lua_tonumber( L, -1 );
lua_pop ( L, 1 );
}
I typed the code blind, so please forgive errors. Also no error checking. But the problem is that I have to do the while loop twice. Is there an easy way to avoid that? I want to optimize for the case where the input is good - a table of ints.
The function you're looking for is unintuitively named lua_objlen, or in Lua 5.2, lua_len (there is a lua_rawlen if you wish to avoid metamethod invocations). It serves many roles (though some, like the length of a string, aren't very useful when you can just use lua_tolstring to get the string and its length), so you should be familiar with it.
ORIGINAL POST
Given that there is no built in function in Lua, I am in search of a function that allows me to append tables together. I have googled quite a bit and have tried every solutions I stumbled across but none seem to work properly.
The scenario goes like this: I am using Lua embeded in an application. An internal command of the application returns a list of values in the form of a table.
What I am trying to do is call that command recursively in a loop and append the returned values, again in the form of a table, to the table from previous iterations.
EDIT
For those who come across this post in the future, please note what #gimf posted. Since Tables in Lua are as much like arrays than anything else (even in a list context), there is no real correct way to append one table to another. The closest concept is merging of tables. Please see the post, "Lua - merge tables?" for help in that regard.
Overcomplicated answers much?
Here is my implementation:
function TableConcat(t1,t2)
for i=1,#t2 do
t1[#t1+1] = t2[i]
end
return t1
end
If you want to concatenate an existing table to a new one, this is the most concise way to do it:
local t = {3, 4, 5}
local concatenation = {1, 2, table.unpack(t)}
Although I'm not sure how good this is performance-wise.
And one more way:
for _,v in ipairs(t2) do
table.insert(t1, v)
end
It seems to me the most readable one - it iterates over the 2nd table and appends its values to the 1st one, end of story. Curious how it fares in speed to the explicit indexing [] above
A simple way to do what you want:
local t1 = {1, 2, 3, 4, 5}
local t2 = {6, 7, 8, 9, 10}
local t3 = {unpack(t1)}
for I = 1,#t2 do
t3[#t1+I] = t2[I]
end
To add two tables together do this
ii=0
for i=#firsttable, #secondtable+#firsttable do
ii=ii+1
firsttable[i]=secondtable[ii]
end
use the first table as the variable you wanted to add as code adds the second one on to the end of the first table in order.
i is the start number of the table or list.
#secondtable+#firsttable is what to end at.
It starts at the end of the first table you want to add to, and ends at the end of the second table in a for loop so it works with any size table or list.
In general the notion of concatenating arbitrary tables does not make sense in Lua because a single key can only have one value.
There are special cases in which concatenation does make sense. One such is for tables containing simple arrays, which might be the natural result of a function intended to return a list of results.
In that case, you can write:
-- return a new array containing the concatenation of all of its
-- parameters. Scaler parameters are included in place, and array
-- parameters have their values shallow-copied to the final array.
-- Note that userdata and function values are treated as scalar.
function array_concat(...)
local t = {}
for n = 1,select("#",...) do
local arg = select(n,...)
if type(arg)=="table" then
for _,v in ipairs(arg) do
t[#t+1] = v
end
else
t[#t+1] = arg
end
end
return t
end
This is a shallow copy, and makes no attempt to find out if a userdata or function value is a container or object of some kind that might need different treatment.
An alternative implementation might modify the first argument rather than creating a new table. This would save the cost of copying, and make array_concat different from the .. operator on strings.
Edit: As observed in a comment by Joseph Kingry, I failed to properly extract the actual value of each argument from .... I also failed to return the merged table from the function at all. That's what I get for coding in the answer box and not testing the code at all.
If you want to merge two tables, but need a deep copy of the result table, for whatever reason, use the merge from another SO question on merging tables plus some deep copy code from lua-users.
(edit
Well, maybe you can edit your question to provide a minimal example... If you mean that a table
{ a = 1, b = 2 }
concatenated with another table
{ a = 5, b = 10 }
should result in
{ a = 1, b = 2, a = 5, b = 10 }
then you're out of luck. Keys are unique.
It seems you want to have a list of pairs, like { { a, 1 }, { b, 2 }, { a, 5 }, { b, 10 } }. You could also use a final structure like { a = { 1, 5 }, b = { 2, 10 } }, depending on your application.
But the simple of notion of "concatenating" tables does not make sense with Lua tables.
)
Here is an implementation I've done similar to RBerteig's above, but using the hidden parameter arg which is available when a function receives a variable number of arguments. Personally, I think this is more readable vs the select syntax.
function array_concat(...)
local t = {}
for i = 1, arg.n do
local array = arg[i]
if (type(array) == "table") then
for j = 1, #array do
t[#t+1] = array[j]
end
else
t[#t+1] = array
end
end
return t
end
Here is my implementation to concatenate a set of pure-integer-indexing tables, FYI.
define a function to concatenate two tables, concat_2tables
another recursive function concatenateTables: split the table list by unpack, and call concat_2tables to concatenate table1 and restTableList
t1 = {1, 2, 3}
t2 = {4, 5}
t3 = {6}
concat_2tables = function(table1, table2)
len = table.getn(table1)
for key, val in pairs(table2)do
table1[key+len] = val
end
return table1
end
concatenateTables = function( tableList )
if tableList==nil then
return nil
elseif table.getn(tableList) == 1 then
return tableList[1]
else
table1 = tableList[1]
restTableList = {unpack(tableList, 2)}
return concat_2tables(table1, concatenateTables(restTableList))
end
end
tt = {t1, t2, t3}
t = concatenateTables(tt)
-- Lua 5.1+
function TableAppend(t1, t2)
-- A numeric for loop is faster than pairs, but it only gets the sequential part of t2
for i = 1, #t2 do
t1[#t1 + 1] = t2[i] -- this is slightly faster than table.insert
end
-- This loop gets the non-sequential part (e.g. ['a'] = 1), if it exists
local k, v = next(t2, #t2 ~= 0 and #t2 or nil)
while k do
t1[k] = v -- if index k already exists in t1 then it will be overwritten
k, v = next(t2, k)
end
end
EDIT
Here's a better solution, the other one tended to overwrite numeric keys, the usage is still the same:
function merge(...)
local temp = {}
local index = 1
local result = {}
math.randomseed(os.time())
for i, tbl in ipairs({ ... }) do
for k, v in pairs(tbl) do
if type(k) == 'number' then
-- randomize numeric keys
k = math.random() * i * k
end
temp[k] = v
end
end
for k, v in pairs(temp) do
if type(k) == "number" then
-- Sort numeric keys into order
if result[index] then
index = index + 1
end
k = index
end
result[k] = v
end
return result
end
ORIGINAL
A wee bit late to the game, but this seems to work for me:
function concat(...)
local result = {}
for i, tbl in ipairs({...}) do
for k, v in pairs(tbl) do
if type(k) ~= "number" then
result[k] = v
else
result[i] = v
end
end
end
return result
end
It might be a bit overcomplicated, but it takes an infinite amount of arguments, and works for both key-value pairs and regular "arrays" (numbers as keys). Here's an example
I like the simplicity in #Weeve Ferrelaine answer, but mutations may cause many issues and in general, are not desirable.
Version with NO MUTATION.
---#param t1 {}
---#param t2 {}
function TableConcat(t1,t2)
local tOut = {}
for i = 1, #t1 do
tOut[i] = t1[i]
end
for i = #t1, #t1 + #t2 do
tOut[i] = t2[i]
end
return tOut
end
Original implementation, that's mutating t1.
function TableConcat(t1,t2)
for i=1,#t2 do
t1[#t1+1] = t2[i]
end
return t1
end
Use table.concat:
http://lua-users.org/wiki/TableLibraryTutorial
> = table.concat({ 1, 2, "three", 4, "five" })
12three4five
> = table.concat({ 1, 2, "three", 4, "five" }, ", ")
1, 2, three, 4, five
> = table.concat({ 1, 2, "three", 4, "five" }, ", ", 2)
2, three, 4, five
> = table.concat({ 1, 2, "three", 4, "five" }, ", ", 2, 4)
2, three, 4