I have trouble to find a good algorithm to get all points around a point(the mid point included) in a coordinate system.
Example:
1 1 2 1 3 1
1 2 2 2 3 2
1 3 2 3 3 3
I have the above grid, so for example if I input: get_around_coordinates(2, 2, 1)
It would return an array which would look like this [[1, 1], [2, 1], [3, 1], [1, 2], [2, 2], [2, 3], [3, 1], [3,2], [3, 3]]
This is how my method looks like:
def get_around_coordinates(px, py, radius)
coord = []
start_x = px - radius
start_y = py - radius
(radius * 2 + 1).times do |x|
(radius * 2 + 1).times do |y|
coord.push([start_x + x, start_y + y])
end
end
return coord
end
I hope that someone can give me something better than this.
Using Array#product:
def get_around_coordinates(px, py, radius)
xs = (px - radius..px + radius).to_a
ys = (py - radius..py + radius).to_a
xs.product(ys)
end
Now let's imagine Ruby lacked this method. The functional approach would be a OOP list-comprehension (flat_map + [flat_map...] + map): xs.flat_map { |x| ys.map { |y| [x, y] } }.
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