Problem in Pluto

[Vos]

Good evening to all,

I have a problem with my code. What I wrote is supposed to draw “lines” connecting the edge of the large rectangle with the edge of the small rectangle, like this:

But sometimes it gives me this, which is not normal:

My code is the following :

begin
	using NativeSVG
    using PlutoUI
end

begin
	const track = zeros(Integer, 49, 49)
	track[1:2,1:49] .= -1
	track[48:49,1:49] .= -1
	track[1:49, 1:2] .= -1
	track[1:49, 48:49] .= -1
	track[12:38, 12:38].= -1
	nothing
end

function Map()
	for row in 1:49
		for col in 1:49
			x = 20 + col * 12
			y = 20 + row * 12
			if track[row, col] === -1
				rect(x = x, y = y, width = 12, height = 12, stroke = "transparent", fill = "black", stroke_width = "0")
			else 
				rect(x = x, y = y, width = 12, height = 12, stroke = "black", fill = "transparent", stroke_width = "0.4")
			end
		end
	end
end

function Line()
	Map()
	a = rand(1:49)
	b = rand(1:49)
	a1 = 20 + a * 12
	b1 = 20 + b * 12
	if track[a, b] ≠ -1
		if a == 3 || a == 39 && b ∈ (12 : 38) 
				while track[a, b] ≠ -1
				a1 = 20 + a * 12
				b1 = 20 + b * 12
				rect(x = a1 + 1, y = b1 + 1, width = 10, height = 10, fill = "red")
				a = a + 1
				end
		elseif a ∈ (12 : 38) && b == 3 || b == 39
			   while track[a, b] ≠ -1
				a1 = 20 + a * 12
				b1 = 20 + b * 12
				rect(x = a1 + 1, y = b1 + 1, width = 10, height = 10, fill = "red")
				b = b + 1
				end
		else 
			Line()
		end
	else 
		Line()
	end
end

Drawing(width = 700, height =700) do
	Line()
end

Do you know where the problem lies or even how to improve this code?
Thanks

[lungben]

In your code, it is not possible for Pluto to detect cell dependencies because all functions work by implicitly modifying the global track variable.
To make Pluto aware of the dependencies, use a more functional approach, i.e. track2= Map(track), where Map takes their inputs as parameters and return the values they modified.
The initialization of track and Line are probably fine because they define / only read the track variable.