Problems on "yoffset * region.numx + xoffset" in SpatialRegionTools.jl, 120

[V-Enzo]

"""
Web Mercator coordinate to cell id
"""
function coord2cell(region::SpatialRegion, x::Float64, y::Float64)
xoffset = round(x - region.minx, digits=6) / region.xstep
yoffset = round(y - region.miny, digits=6) / region.ystep
xoffset = convert(Int, floor(xoffset))
yoffset = convert(Int, floor(yoffset))
yoffset * region.numx + xoffset
end
Hi @boathit , in your preprocessing part in file SpatialRegionTools.jl line 120, I feel confused when you project coordinates into cells here. From my understanding, every cell we defined should be assigned an
id, which could be from 0 to vocab_size-1. But here the id equals yoffset * region.numx + xoffset. Why is this? Thank you.

[boathit]

The cell id does not range over [0, vocab_size-1], it is transformed into vocabulary in this line.

[V-Enzo]

The cell id does not range over [0, vocab_size-1], it is transformed into vocabulary in this line.

@boathit I see, so the cell id is related to the number of the size of hot cell. If I set the hyper parameter of frequent to 1, which means I take every cell of the map into consideration. Will the vocab size be equal to the number of all cells on the map? Meanwhile, I still don't understand why do you transform coordinates to cell id by yoffset * region.numx + xoffset ? Really appreciate it if you could explain this. Thank you.

[boathit]

For the first question, the answer is yes. Transforming coordinates into cell ids is just the process of discretization, in which (xoffset, yoffset) is the cell coordinate and region.numx is the number of columns, yoffset * region.numx + xoffset simply transforms the 2D array into a 1D array.

[V-Enzo]

Thanks. I know your main idea now. Appreciate it!