I am trying to write a simple game using Love 2d engine. It uses lua as the scripting language. I have some problems with arrays and can't find any solution. Here is my issue:
for i = 1, 10 do
objects.asteroids = {}
objects.asteroids[i] = {}
objects.asteroids[i].body = love.physics.newBody(world, 650/2, 650/2, "dynamic")
objects.asteroids[i].size = 3
objects.asteroids[i].angle = math.random(6)
end
In the same function I am trying to do a following operation:
for i = 1, 10 do
objects.asteroids[i].size = 2
end
And I get this error when trying to run my game:
Error
main.lua:48: attempt to index a nil value
Where line 48 refers to this line of code:
objects.asteroids[i].size = 2
You're overwriting objects.asteroids on each loop iteration.
for i = 1, 10 do
objects.asteroids = {} -- <== Here.
objects.asteroids[i] = {}
What this means is that the asteroid objects that you're trying to add end up being erased on the next step of the loop, since object.asteroids is set to a new {} table and the old one becomes inaccessible thereafter.
You might want to rearrange it like so:
objects.asteroids = {}
for i = 1, 10 do
objects.asteroids[i] = {}
-- ...
Related
I Want to copy an array from a text file and make another array equal it
so
local mapData = {
grass = {
cam = "hud",
x = 171,
image = "valley/grass",
y = 168,
animated = true
}
}
This is an array that is in Data.lua
i want to copy this array and make it equal another array
local savedMapData = {}
savedMapData = io.open('Data.lua', 'r')
Thank you.
It depends on Lua Version what you can do further.
But i like questions about file operations.
Because filehandlers in Lua are Objects with methods.
The datatype is userdata.
That means it has methods that can directly be used on itself.
Like the methods for the datatype string.
Therefore its easy going to do lazy things like...
-- Example open > reading > loading > converting > defining
-- In one Line - That is possible with methods on datatype
-- Lua 5.4
local savedMapData = load('return {' .. io.open('Data.lua'):read('a'):gsub('^.*%{', ''):gsub('%}.*$', '') .. '}')()
for k, v in pairs(savedMapData) do print(k, '=>', v) end
Output should be...
cam => hud
animated => true
image => valley/grass
y => 168
x => 171
If you need it in the grass table then do...
local savedMapData = load('return {grass = {' .. io.open('Data.lua'):read('a'):gsub('^.*%{', ''):gsub('%}.*$', '') .. '}}')()
The Chain of above methods do...
io.open('Data.lua') - Creates Filehandler (userdata) in read only mode
(userdata):read('a') - Reading whole File into one (string)
(string):gsub('^.*%{', '') - Replace from begining to first { with nothing
(string):gsub('%}.*$', '') - Replace from End to first } with nothing
I have two sets of arrays stored in a file and I need to extract values one by one and compare them. I am using this code but does look like I am doing correctly.
# First Dataset
File.foreach(file_set_a) do |data_a|
data_array_a = data_a.split("\t")
#file_name_a = data_array_a[0]
#file_ext_a = data_array_a[1]
# Second Dataset
File.foreach(file_set_b) do |data_b|
data_array_b = data_b.split("\t")
#file_name_b = data_array_b[0]
#file_ext_b = data_array_b[1]
#Compare
#file_name_a == #file_name_b
end
end
The problem is, I cannot go back and extract the next values in the set A when I enter the set B. Any suggestions?
First, convert those 2 files into two separated data arrays
lines_array_a = File.readlines(file_set_a)
lines_array_b = File.readlines(file_set_b)
I am assuming both of the array size will be same. Now run a loop and get the items from both array to compare them.
for i in 0..(lines_array_a.count - 1) do
data_array_a = lines_array_a[i].split("\t")
#file_name_a = data_array_a[0]
#file_ext_a = data_array_a[1]
data_array_b = lines_array_b[i].split("\t")
#file_name_b = data_array_b[0]
#file_ext_b = data_array_b[1]
#file_name_a == #file_name_b
end
I'm getting a very irritating error whenever I do anything like this with arrays. I have code that sets up the array in the love.load() function:
function iceToolsInit()
objectArray = {} --for object handling
objectArrayLocation = 0
end
and then code that allows for the creation of an object. It basically grabs all of the info about said object and plugs it into an array.
function createObject(x, y, renderimage) --used in the load function
--objectArray is set up in the init function
objectArrayLocation = objectArrayLocation + 1
objectArray[objectArrayLocation] = {}
objectArray[objectArrayLocation]["X"] = x
objectArray[objectArrayLocation]["Y"] = y
objectArray[objectArrayLocation]["renderimage"] =
love.graphics.newImage(renderimage)
end
After this, an update function reads through the objectArray and renders the images accordingly:
function refreshObjects() --made for the update function
arrayLength = #objectArray
arraySearch = 0
while arraySearch <= arrayLength do
arraySearch = arraySearch + 1
renderX = objectArray[arraySearch]["X"]
renderY = objectArray[arraySearch]["Y"]
renderimage = objectArray[arraySearch]["renderimage"]
if movingLeft == true then --rotation for rightfacing images
renderRotation = 120
else
renderRotation = 0
end
love.graphics.draw(renderimage, renderX, renderY, renderRotation)
end
end
I of course clipped some unneeded code (just extra parameters in the array such as width and height) but you get the gist. When I set up this code to make one object and render it, I get this error:
attempt to index '?' (a nil value)
the line it points to is this line:
renderX = objectArray[arraySearch]["X"]
Does anyone know what's wrong here, and how I could prevent it in the future? I really need help with this.
It's off-by-one error:
arraySearch = 0
while arraySearch <= arrayLength do
arraySearch = arraySearch + 1
You run through the loop arrayLength+1 number of times, going through indexes 1..arrayLength+1. You want to go through the loop only arrayLength number of times with indexes 1..arrayLength. The solution is to change the condition to arraySearch < arrayLength.
Another (more Lua-ly way) is to write this as:
for arraySearch = 1, #objectArray do
Even more Lua-ly way is to use ipairs and table.field reference instead of (table["field"]):
function refreshObjects()
for _, el in ipairs(objectArray) do
love.graphics.draw(el.renderimage, el.X, el.Y, movingLeft and 120 or 0)
end
end
objectArray and movingLeft should probably be passed as parameters...
I will try to as concise as possible with my issue.
Firstly, files are:
block.lua
base.lua
main.lua
In block.lua I create a block, add collision detection and a cleanup code.
In base.lua I create a base made up of 4 columns and 10 rows. 40 blocks in total.
In main.lua I create 4 bases made from the base.class.
All is working fine once the game begins.
I remove the bases and call them again on level 2.
They create themselves ok BUT
when the enemy is destroyed once again, and the bases are to be rebuilt, I get an:
array index 1 is beyond array bounds:1..1
-- all the way up to--
array index 800 is beyond array bounds:1..159
it will then create the bases and continue until the enemys are destroyed and do the same again starting at :
array index 800 is beyond array bounds:1..159
-- all the way up to--
array index 4000 is beyond array bounds:1..159
The terminal points me at block.lua line 23
blockGroup:insert(blockNum,self.block)
Now I cant see anything wrong in the class, I have looked and googled for hours but all to no avail.
I would really appreciate a helping hand to guide me here please.
I have tried rewriting the "cleanup" etc but no joy.
I left a few commented out bits in there and removed some of the irrelevant stuff.
I post below the relevant code:
--MAIN.LUA--
function gameOver()
Runtime:removeEventListener("enterFrame", onEnterFrame)
Runtime:removeEventListener("enterFrame", movePlayer)
layers:removeSelf()
layers = nil
enemyCount = 0
for i = 1,#allEnemys do
timer.cancel(allEnemys[i].clock)
Runtime:removeEventListener( "enterFrame", allEnemys[i] )
display.remove(allEnemys[i].image)
allEnemys[i].image=nil
end
allEnemys=nil
cleanupBlocks()
end
----------------------------------------------------------------------
-- LEVEL UP --
----------------------------------------------------------------------
function levelUp(level)
enemyCount = 0
local enemys = require("modules.enemy")
if allEnemys ~= nil then
for i = 1,#allEnemys do
timer.cancel(allEnemys[i].clock)
Runtime:removeEventListener( "enterFrame", allEnemys[i] )
display.remove(allEnemys[i].image)
allEnemys[i].image=nil
end
end
allEnemys=nil
cleanupBlocks()
levels()
end
----------------------------------------------------------------------
-- LEVELS --
----------------------------------------------------------------------
function levels(level)
function createInvader(x, y, row)
for j = 1, 2 do
for i = 1, 2 do
if allEnemys == nil then
allEnemys = {}
else
enemysCount=#allEnemys
end
allEnemys[#allEnemys + 1] = enemys:new()
allEnemys[#allEnemys ]:init(i * 60, j * 70 + 70,j)
allEnemys[#allEnemys ]:start()
end
end
end
createInvader()
--[[function createBases1()
local base = require("modules.base")
for i = 1, 4 do
base:new()
base:init(i * 180 - 130, 850)
end
end ]]--
createBases()
end
--BLOCK.LUA--
local block = {}
local block_mt = { __index = block}
local scene = scene
local blockGroup = display.newGroup()
local blockNum = 0
function block:new() -- constructor
local group = {}
return setmetatable( group, block_mt )
end
function block:init(xloc,yloc) --initializer
-- Create attributes
self.block = display.newRect( xloc,yloc,10,10)
self.block:setFillColor ( 2, 255, 14 )
blockNum = blockNum + 1
blockGroup:insert(blockNum,self.block)
local blockCollisionFilter = { categoryBits = 128, maskBits = 387}
physics.addBody( self.block, "static", {filter = blockCollisionFilter})
self.count = 1
end
function cleanupBlocks()
--[[ print(blockNum, blockGroup.numChildren)
for i=1,blockGroup.numChildren do
blockGroup[1]:removeSelf()
blockGroup[1] = nil
end ]]--
print(blockNum, blockGroup.numChildren)
while blockGroup.numChildren>0 do
display.remove(blockGroup[1])
blockGroup[1]=nil
end
end
function block:start()
--- Create Listeneres
self.block:addEventListener( "collision", self )
scene:addEventListener('base_block_event', self)
end
return block
--BASE.LUA--
local base = {}
local base_mt = { __index = base}
local scene = scene
local block = require("modules.block")
function base:new() -- constructor
local group = {}
return setmetatable( group, base_mt )
end
function base:init(xloc, yloc) --initializer
-- Create attributes
local base
for j = 1, 4 do
for i = 1, 10 do
base = block:new()
base:init(xloc+i * 10,yloc+j * 10)
base:start()
end
end
end
return base
I see you use
blockNum = blockNum + 1
blockGroup:insert(blockNum,self.block)
Try to use
blockGroup:insert(self.block)
just to see if you still get that error.
I am trying to write a short code to read a .m file(testin1.m) into an array, and search for a particular word( 'auto'). if match is found,delete it. i have the following code, please help me figure out my mistake.
fid = fopen('testin1.m');
txt = textscan(fid,'%s');
fclose(fid);
m_file_idx = 1;
data=['auto'];
B=cellstr(data);
for idx = i : length(txt)
A=txt{i};
is_auto=isequal(A, B);
if is_auto==0
txt{i}=[];
end
end
if txt{i}=auto then it should delete that row.
AK4749's answer is absolutely correct in showing where you went wrong. I'll just add an alternative solution to yours, which is shorter:
C = textread('testin1.m', '%s', 'delimiter', '\n');
C = C(cellfun(#isempty, regexp(C, 'auto')));
That's it!
EDIT #1: answer modified to remove the lines that contains the word 'auto', not just the word itself.
EDIT #2: answer modified to accept regular expressions.
This is an error i have hit many amany many many times:
when you set txt(i) = [], you change the length of the array. Your for loop condition is no longer valid.
A better option would be to use the powerful indexing features:
A(find(condition)) = [];
or account for the change in length:
A(i) = [];
i--; % <-- or i++, it is too early to think, but you get the idea
EDIT: I just noticed you were also using A in your program. mine was just some random variable name, not the same A you might be using
When you set txt(i) = [], you changed the length of the array but the loop indexing does not account for the change. You can use logical indexing to avoid the loop and the problem.
Example:
wordToDelete = 'auto';
txt = {'foo', 'bar', 'auto', 'auto', 'baz', 'auto'}
match = strcmp(wordToDelete, txt)
txt = txt(~match)
Output:
txt =
'foo' 'bar' 'auto' 'auto' 'baz' 'auto'
match =
0 0 1 1 0 1
txt =
'foo' 'bar' 'baz'