for x = 1, 16 do
for y = 1, 16 do
local cntr = Center:new()
cntr.point = {x = 0.5 + x - 1, y = 0.5 + y - 1}
centerLookup[cntr.point] = cntr
table.insert(self.centers, cntr)
end
end
In the code above, centerLookup[point] is meant to look up the respective Center object by inputting a point location.
However, when I try to do this:
function neighbors(center, sqrtsize)
if center.point.y + 1 < sqrtsize then
local up = {x = center.point.x, y = center.point.y+1}
local centerup = centerLookup[up]
table.insert(center.neighbors, centerup)
end
end
centerup returns as a nil value
Idk if the problem is that I can't use a table as an index, but that is what I'm thinking.
Anybody know what's wrong here?
P.S. if it's helpful, centers start at 0.5 (so [0.5, 0.5] would be the first center, then [0.5, 1.5], etc.)
Thanks in advance!
This has nothing to do with local variables and everything to do with the fact that tables are compared by-reference and not by-value.
In Lua, tables are reference types that have their own identity. Even if two tables have the same contents, Lua does not consider them equal unless they are the exact same object.
To illustrate this, here is some sample code, and the printed values:
local tbl1 = {x = 0.5, y = 0.5}
local tbl2 = tbl1
local tbl3 = {x = 0.5, y = 0.5}
print(tbl1 == tbl2) -- True; tbl1 and tbl2 both reference the same table
print(tbl1 == tbl3) -- False; tbl1 and tbl3 reference different tables
local up = {x = center.point.x, y = center.point.y+1}
local centerup = centerLookup[up]
In this snippet, up is a completely new table with only one reference (the up variable itself). This new table won't be a key in your centerLookup table, even if a table key exists with the same contents.
cntr.point = {x = 0.5 + x - 1, y = 0.5 + y - 1}
centerLookup[cntr.point] = cntr
table.insert(self.centers, cntr)
In this snippet, you create a new table, and reference it in three different places: cntr.point, centerLookup as a key, and self.centers as a value. You presumably iterate through the self.centers array, and use the exact same table to look up items in the centerLookup table. However, if you were to use a table not in the self.centers array, it would not work.
Colonel Thirty Two explained the reason why your code not working as expected. I just want to add quick solution:
function pointToKey(point)
return point.x .. "_" .. point.y
end
Use this function for lookup in both places
--setup centerLookup
centerLookup[pointToKey(cntr.point)] = cntr
--find point from lookup
local centerup = centerLookup[pointToKey(up)]
Related
I'm currently trying to create brick breaker using love2d but the problem is whenever is used math.random() to generate random bricks the love application keeps running it multiple times and the brick moves constantly.
EDIT: So I want to generate bricks at particular column but the rows should be randomly selected. My basic idea was to do math.random(2) == 1 then drawing bricks using for loop but the problem is that it gets updated/drawn at every second and the bricks keeps on flickering/moving. I just want to randomly(only randomly select the y co-ordinate my x co-ordinate is fixed) to draw it once when you execute the code but its keep on flickering
The issue I'm facing - https://youtu.be/AJB5vH7yfHc
My code
for y = 0, VIRTUAL_HEIGHT- 4, 10 do
if math.random(2) == 1 then
love.graphics.rectangle('line', VIRTUAL_WIDTH - 10, y, 5, 10)
end
end
Alright, after you edited the question, this sounds more like what you're talking about. Just take out that #column loop, and set it to create cells on the last column.
love.load()
--VIRTUAL_WIDTH, VIRTUAL_HEIGHT = love .graphics .getDimensions()
block_pos = {} -- table to store block positions
rows, columns = 30, 20 -- you decide how many
chance_of_block = 33 -- % chance of placing a block
block_width = math .floor( VIRTUAL_WIDTH /columns )
block_height = math .floor( VIRTUAL_HEIGHT /rows )
col = columns -1 -- don't loop through columns, just use final column
for row = 0, rows -1 do
if love .math .random() *100 <= chance_of_block then
local xpos = col *block_width
local ypos = row *block_height
block_pos[ #block_pos +1 ] = { x = xpos, y = ypos }
end -- rand
end -- #columns
r, g, b = 0.5, 0.5, 0.0
love .graphics .setColor( r, g, b )
love.draw()
for b = 1, #block_pos do
local block = block_pos[b]
love .graphics .rectangle( 'line', block.x, block.y, block_width, block_height )
end -- #block_pos
generate block positions in love.load()
--VIRTUAL_WIDTH, VIRTUAL_HEIGHT = love .graphics .getDimensions( )
block_pos = {} -- table to store block positions
rows, columns = 5, 8 -- you decide how many
chance_of_block = 75 -- % chance of placing a block
block_width = math .floor( VIRTUAL_WIDTH /columns )
block_height = math .floor( VIRTUAL_HEIGHT /rows )
for row = 0, rows -1 do
for col = 0, columns -1 do
if love .math .random() *100 <= chance_of_block then
local xpos = col *block_width
local ypos = row *block_height
local red = love .math .random()
local green = love .math .random()
local blue = love .math .random()
block_pos[ #block_pos +1 ] = { x = xpos, y = ypos, r = red, g = green, b = blue }
end -- rand
end -- #columns
end -- #rows
(edited: realized row & column should start from 0 index, so they line up on the screen)
then draw them with love.draw()
for b = 1, #block_pos do
local block = block_pos[b]
love .graphics .setColor( block.r, block.g, block.b )
love .graphics .rectangle( 'fill', block.x, block.y, block_width, block_height )
end -- #block_pos
WARNING: This question is only for Touch Lua users who have purchased and have knowledge of the Draw Library.
PLEASE REFER TO THE BOTTOM PORTION OF THIS QUESTION TO SEE THE FULL PROGRAM. THE SNIPPETS I USE IN THE BEGINNING ARE PART OF THAT PROGRAM (NUMPAD.LUA)
Okay, so now for the questions:
•What's the use of "." between "b" and "x"? Or "b" and "draw"? Etc...
•How does the table set up the button? Please be super specific?
•Why is there a "+", "*", and "(j-1)" in lines 7 and 8?
•What's height and width doing in there? I thought there were only x and y.
function createButtons()
buttons = { }
local c = 1
for i = 1, 4 do
for j = 1, 3 do
local b = { }
b.x = 80 + 60 * (j-1)
b.y = 160 + 60 * (i-1)
b.width = 40
b.height = 40
b.color = draw.blue
b.draw = drawButton
b.action = digitAction
buttons[c] = b
c = c + 1
end
end
buttons[1].title = '7'
buttons[2].title = '8'
buttons[3].title = '9'
buttons[4].title = '4'
buttons[5].title = '5'
buttons[6].title = '6'
buttons[7].title = '1'
buttons[8].title = '2'
buttons[9].title = '3'
buttons[10].title = '0'
buttons[11].title = '.'
buttons[11].action = dotAction
buttons[12].title = 'C'
buttons[12].color = draw.orange
buttons[12].action = clearAction
end
Lastly, referencing the program as a whole...
•How does the button know when you tap on it? Specifically what are the lines of code and how does it work? (I have a very faint understanding of track touches btw)
function digitAction(button)
if string.len(display.title) < 16 then
sys.alert('tock')
if display.started then
display.title = display.title .. button.title
else
if button.title ~= '0' then
display.title = button.title
display.started = true
end
end
else
sys.alert('tink')
end
end
function dotAction(button)
if string.find(display.title, '.', 1, true) then
sys.alert('tink')
else
display.title = display.title .. '.'
display.started = true
sys.alert('tock')
end
end
function clearAction(button)
sys.alert('tock')
display.title = '0'
display.started= false
end
function createDisplay()
display = { }
display.x = 60
display.y = 100
display.width = 200
display.height = 40
display.title = '0'
display.color = draw.red
display.started = false
end
function createButtons()
buttons = { }
local c = 1
for i = 1, 4 do
for j = 1, 3 do
local b = { }
b.x = 80 + 60 * (j-1)
b.y = 160 + 60 * (i-1)
b.width = 40
b.height = 40
b.color = draw.blue
b.draw = drawButton
b.action = digitAction
buttons[c] = b
c = c + 1
end
end
buttons[1].title = '7'
buttons[2].title = '8'
buttons[3].title = '9'
buttons[4].title = '4'
buttons[5].title = '5'
buttons[6].title = '6'
buttons[7].title = '1'
buttons[8].title = '2'
buttons[9].title = '3'
buttons[10].title = '0'
buttons[11].title = '.'
buttons[11].action = dotAction
buttons[12].title = 'C'
buttons[12].color = draw.orange
buttons[12].action = clearAction
end
function drawDisplay()
draw.setfont('Helvetica', 20)
draw.setlinestyle(2, 'butt')
local x1, y1 = display.x, display.y
local x2, y2 = x1 + display.width, y1 + display.height
draw.roundedrect(x1, y1, x2, y2, 10, display.color)
local w, h = draw.stringsize(display.title)
local x = x2 - 10 - w
local y = y1 + (display.height - h)/2
draw.string(display.title, x, y, draw.black)
end
function drawButton(b)
draw.setfont('Helvetica', 18)
draw.setlinestyle(2, 'butt')
local x1, y1 = b.x, b.y
local x2, y2 = x1+b.width, y1+b.height
draw.roundedrect(x1, y1, x2, y2, 10, b.color)
local w, h = draw.stringsize(b.title)
local x = b.x + (b.width - w)/2
local y = b.y + (b.height - h)/2
draw.string(b.title, x, y, draw.black)
end
function drawButtons()
for i = 1, #buttons do
buttons[i].draw(buttons[i])
end
end
function lookupButton(x, y)
for i = 1, #buttons do
local b = buttons[i]
if x > b.x and x < b.x+b.width and y > b.y and y < b.y+b.height then
return b
end
end
return nil
end
function drawScreen()
draw.beginframe()
draw.clear()
drawDisplay()
drawButtons()
draw.endframe()
end
function touchBegan(x, y)
local b = lookupButton(x, y)
if b then
b.action(b)
end
end
function touchMoved(x, y)
end
function touchEnded(x, y)
end
function init()
draw.setscreen(1)
draw.settitle('Num Pad')
draw.clear()
draw.tracktouches (touchBegan, touchMoved, touchEnded)
createButtons()
createDisplay()
end
function mainloop()
while true do
draw.doevents()
drawScreen()
draw.sleep(30)
end
end
function main()
init()
mainloop()
end
-- start program
main()
Thank you so much for any help you can offer! I know this is a lot of questions, but this knowledge can really help propel me forward!
WARNING: This question is only for Touch Lua users who have purchased
and have knowledge of the Draw Library
Since when do you have to purchase something to answer programming questions? All your questions are on absolute Lua basics anyway.
What's the use of "." between "b" and "x"? Or "b" and "draw"? Etc...
The dot operator is used to index table members. So b.x will give you the value that belongs to key "x" in table b. Its syntactic sugar for b["x"].
How does the table set up the button? Please be super specific?
The function createButtons creates an empty table and fills it with buttons represented by a table b that stores various button properties.
Why is there a "+", "*", and "(j-1)" in lines 7 and 8?
Because the author of that program wants to add and multiply. Here the coordinates b.x and b.y are calculated. (j-1) is used because j starts at 1, but he needs it to start at 0 for this calculation.
The 2 for loops will create 4 rows of buttons, each containing 3 buttons as the x coordinate depends on parameter j while y depends on parameter i.
What's height and width doing in there? I thought there were only x
and y.
The button needs dimensions, not only a location. As b is created as a local variable within the for loop all its properties are set here. They may be changed later.
How does the button know when you tap on it? Specifically what are the
lines of code and how does it work?
Your mainloop will call draw.doevents() every cycle. So at some point there will be an event that will cause touchBegan to be called.
The button itself does not know that it was tapped. function touchBegan(x,y) will search if one of the buttons was hit at x,y by calling lookupButton(x,y) and call its action function. action is either one of dotAction, digitAction or clearAction. So if you tap on a digit button digitAction() will be called e.g.
Do yourself a favour and read a book on Lua or at least do a Lua tutorial. Befor diving into third party libraries. If you don't know how to index the most common Lua type or that + and * are arrithmetic operators, you will have a very hard time understanding code and you will not be productive in any way.
This program in particular uses tables to represent buttons, it does this to make it more manageable. The height and width are the same way. If you are new to the draw library, reviewing code like this is only going to confuse you. Most of your questions are actually about OOP honestly
Also this question probably isn't suitable for Stack Overflow right now. If you want help/a small tutorial on the subject feel free to PM me on the Touch Lua forum, my username is warspyking, but as it stands you need to either revise or delete this question.
How can I sort 2 lists y location ( map tiles and people ) and draw them in order dependent of y. 2 lists I want to use:
map = {}
map.y = {60,10,40,80}
map.t = {0,0,1,1} -- type
people = {}
people.y = {0,100}
people.t = {0,1} -- type
I can currently sort and draw a single list of hero and boxes.
Sort / draw code:
box1 = love.graphics.newImage("box1.png")
box2 = love.graphics.newImage("box2.png")
box3 = love.graphics.newImage("box3.png")
hero = love.graphics.newImage("hero.png")
object = {
x = {0, 50,100,200},
y = {0,200, 50,100},
g = {0,1,2,3}
}
function sortIndex(item)
local i
local id = {} -- id list
for i = 1, #item.x do -- Fill id list (1 to length)
id[i] = i
end
-- print( unpack(id) ) -- Check before
table.sort(id,sortY)-- Sort list
-- print( unpack(id) ) -- Check after
item.sort = id -- List added to object.sort
-- Sort id, using item values
function sortY(a,b)
return item.y[a] < item.y[b]
end
end
function drawObject()
local i,v, g,x,y
for i = 1, #object.x do
v = object.sort[i] -- Draw in order
x = object.x[v]
y = object.y[v]
g = object.g[v]
if g == 0 then g = hero -- set to an image value
elseif g == 1 then g = box1
elseif g == 2 then g = box2
elseif g == 3 then g = box3
end
love.graphics.draw(g,x,y,0,7,7)
end
end
Update sort:
sortIndex(object)
My function sorts an id list comparing a y location list. The id is used to draw objects in order dependent of their y. How can I sort 2 id lists together comparing 2 y location lists, then draw them in order?
Maybe when drawing, switch from map tiles to people dependent on y, but I don't know how.
Might be related to your previous question a lot: Returning A Sorted List's Index in Lua
I assume if your height can be 1,2 and 3 (with 1 being on the top), you first want to render all tiles at Y1, then all people at Y1, then Y2 and Y3. To do that, you'll have to make a combined list and sort that:
map = {}
map.y = {60,10,40,80}
map.t = {0,0,1,1} -- type
people = {}
people.y = {0,100}
people.t = {0,1} -- type
local all = {}
local map_y = map.y
local offset = #map_y
local people_y = people.y
-- Fill the list with map tiles
for i=1,offset do
all[i] = {1,i,map_y[i]} --{type,index,y}
end
-- Fill the list with people
for i=1,#people_y do
all[i+offset] = {2,i,people_y[i]}
end
-- Do the sorting
-- It works a bit like your previous question:
-- 'all' contains "references":
-- They tell us is it's from map/people + the index
-- We sort the references using the third element in it:
-- The 'y' variable we put there during the first 2 loops
table.sort(all,function(a,b)
return a[3] < b[3]
end)
-- Printing example
-- The references are sorted using the 'y' field of your objects
-- With v[1] we know if it's from map/people
-- The v[2] tells us the index in that ^ table
-- The v[3] is the 'y'-field. No real need to remove it
for k,v in pairs(all) do
print(v[1] == 1 and "Map" or "Person",v[2],"with y being",v[3])
end
Output:
Person 1 with y being 0
Map 2 with y being 10
Map 3 with y being 40
Map 1 with y being 60
Map 4 with y being 80
Person 2 with y being 100
There are 2 things I want to add, that doesn't have anything to do with the question of my answer:
Maybe it would be easier if you have a table for each element.
Your people would be {0,0} and {100,1} which might be easier to manipulate.
If you prefer your stuff always sorted, you might want to use this: Sorted List. If you keep a sorted list of all your objects, you don't have to sort the list everytime you add/remove an element, or worse, each time you render. (depending if people move) This might help with performance if you're planning to have a lot of map/people objects. (Sorted List could be useful for your current data system, but also the {y=1,t=1} one)
function sortIndex(...)
sorted = {} -- global
local arrays_order = {}
for arr_index, array in ipairs{...} do
arrays_order[array] = arr_index
for index = 1, #array.y do
table.insert(sorted, {array = array, index = index})
end
end
table.sort(sorted,
function (a,b)
local arr1, arr2 = a.array, b.array
local ind1, ind2 = a.index, b.index
return arr1.y[ind1] < arr2.y[ind2] or
arr1.y[ind1] == arr2.y[ind2] and arrays_order[arr1] < arrays_order[arr2]
end)
end
function drawAll()
for _, elem_info in ipairs(sorted) do
local array = elem_info.array
local index = elem_info.index
local x = array.x[index]
local y = array.y[index]
if array == map then
-- draw a map tile with love.graphics.draw()
elseif array == people then
-- draw a human with love.graphics.draw()
end
end
end
sortIndex(map, people) -- to draw map tiles before people for the same y
I am using Excel 2007 which supports Columns upto 16,384 Columns. I would like to obtain the Column name corresponding Column Number.
Currently, I am using the following code. However this code supports upto 256 Columns. Any idea how to obtain Column Name if the column number is greater than 256.
function loc = xlcolumn(column)
if isnumeric(column)
if column>256
error('Excel is limited to 256 columns! Enter an integer number <256');
end
letters = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
count = 0;
if column-26<=0
loc = char(letters(column));
else
while column-26>0
count = count + 1;
column = column - 26;
end
loc = [char(letters(count)) char(letters(column))];
end
else
letters = ['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
if size(column,2)==1
loc =findstr(column,letters);
elseif size(column,2)==2
loc1 =findstr(column(1),letters);
loc2 =findstr(column(2),letters);
loc = (26 + 26*loc1)-(26-loc2);
end
end
Thanks
As a diversion, here is an all function handle example, with (almost) no file-based functions required. This is based on the dec2base function, since Excel column names are (almost) base 26 numbers, with the frustrating difference that there are no "0" characters.
Note: this is probably a terrible idea overall, but it works. Better solutions are probably found elsewhere in the file exchange.
First, the one file based function that I couldn't get around, to perform arbitrary depth function composition.
function result = compose( fnHandles )
%COMPOSE Compose a set of functions
% COMPOSE({fnHandles}) returns a function handle consisting of the
% composition of the cell array of input function handles.
%
% For example, if F, G, and H are function handles with one input and
% one output, then:
% FNCOMPOSED = COMPOSE({F,G,H});
% y = FNCOMPOSED(x);
% is equivalent to
% y = F(G(H(x)));
if isempty(fnHandles)
result = #(x)x;
elseif length(fnHandles)==1
result = fnHandles{1};
else
fnOuter = fnHandles{1};
fnRemainder = compose(fnHandles(2:end));
result = #(x)fnOuter(fnRemainder(x));
end
Then, the bizarre, contrived path to convert base26 values into the correct string
%Functions leading to "getNumeric", which creates a numeric, base26 array
remapUpper = #(rawBase)(rawBase + (rawBase>='A')*(-55)); %Map the letters 'A-P' to [10:26]
reMapLower = #(rawBase)(rawBase + (rawBase<'A')*(-48)); %Map characters '0123456789' to [0:9]
getRawBase = #(x)dec2base(x, 26);
getNumeric = #(x)remapUpper(reMapLower(getRawBase(x)));
%Functions leading to "correctNumeric"
% This replaces zeros with 26, and reduces the high values entry by 1.
% Similar to "borrowing" as we learned in longhand subtraction
borrowDownFrom = #(x, fromIndex) [x(1:(fromIndex-1)) (x(fromIndex)-1) (x(fromIndex+1)+26) (x((fromIndex+2):end))];
borrowToIfNeeded = #(x, toIndex) (x(toIndex)<=0)*borrowDownFrom(x,toIndex-1) + (x(toIndex)>0)*(x); %Ugly numeric switch
getAllConditionalBorrowFunctions = #(numeric)arrayfun(#(index)#(numeric)borrowToIfNeeded(numeric, index),(2:length(numeric)),'uniformoutput',false);
getComposedBorrowFunction = #(x)compose(getAllConditionalBorrowFunctions(x));
correctNumeric = #(x)feval(getComposedBorrowFunction(x),x);
%Function to replace numerics with letters, and remove leading '#' (leading
%zeros)
numeric2alpha = #(x)regexprep(char(x+'A'-1),'^#','');
%Compose complete function
num2ExcelName = #(x)arrayfun(#(x)numeric2alpha(correctNumeric(getNumeric(x))), x, 'uniformoutput',false)';
Now test using some stressing transitions:
>> num2ExcelName([1:5 23:28 700:704 727:729 1024:1026 1351:1355 16382:16384])
ans =
'A'
'B'
'C'
'D'
'E'
'W'
'X'
'Y'
'Z'
'AA'
'AB'
'ZX'
'ZY'
'ZZ'
'AAA'
'AAB'
'AAY'
'AAZ'
'ABA'
'AMJ'
'AMK'
'AML'
'AYY'
'AYZ'
'AZA'
'AZB'
'AZC'
'XFB'
'XFC'
'XFD'
This function I wrote works for any number of columns (until Excel runs out of columns). It just requires a column number input (e.g. 16368 will return a string 'XEN').
If the application of this concept is different than my function, it's important to note that a column of x number of A's begins every 26^(x-1) + 26^(x-2) + ... + 26^2 + 26 + 1. (e.g. 'AAA' begins on 26^2 + 26 + 1 = 703)
function [col_str] = let_loc(num_loc)
test = 2;
old = 0;
x = 0;
while test >= 1
old = 26^x + old;
test = num_loc/old;
x = x + 1;
end
num_letters = x - 1;
str_array = zeros(1,num_letters);
for i = 1:num_letters
loc = floor(num_loc/(26^(num_letters-i)));
num_loc = num_loc - (loc*26^(num_letters-i));
str_array(i) = char(65 + (loc - 1));
end
col_str = strcat(str_array(1:length(str_array)));
end
Hope this saves someone some time!
I have a list of data points that are to represent a probability distribution. I need to integrate over this distribution. However since I didn't have a function and I only had a set of data points, I came up with the following code to represent the probability distribution:
dList1 = Import["Z-1.txt", "Table"];
dList2 = Import["Z_over-1.txt", "Table"];
dDist[X_,sym_] := (
dList = 0;
If[sym,
dList = dList1;
,
dList = dList2;
];
val = 0;
If[Abs[X] < Pi,
i = 2;
While[dList[[i]][[1]] < X, i++];
width = dList[[i]][[1]] - dList[[i-1]][[1]];
difX = dList[[i]][[1]] - X;
difY = dList[[i]][[2]] - dList[[i-1]][[2]];
val = dList[[i-1]][[2]] + (1-(difX/width)) difY;
];
Return[val];
);
where the set of data points are in the text files.
Performing the following command:
Plot[dDist[x, True], {x, -1, 1}]
gives this:
Whereas, performing this:
NIntegrate[dDist[x, True], {x, -1, 1}]
evaluates to zero, along with this warning:
I have tried increasing MinRecursion to no avail. I'm not sure what to do and would be open to any suggestions, including modifying the dDist function.
Not having your data to play with, I'd suggest using the table(s) to create Piecewise functions separated at the disontinuities. NIntegrate should handle those with no problem.