How to randomly draw something once in love2d - random

Question

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

Answer 1

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

Answer 2

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