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Fix GeoPatch algorithm #264

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Apr 19, 2022
Merged

Fix GeoPatch algorithm #264

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e93bf68
Fix GeoPatch algorithm
Neylix Mar 24, 2022
488f860
Update geo patch calculation
Neylix Apr 3, 2022
094d088
update geo patch tests
Neylix Apr 3, 2022
9896535
Switch env value to config
Neylix Apr 4, 2022
e5b0d04
Correct out of bound index
Neylix Apr 5, 2022
7e67cde
Convert list to tuple to improve execution time
Neylix Apr 7, 2022
6b722f9
Add near location city in test
Neylix Apr 8, 2022
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74 changes: 20 additions & 54 deletions lib/archethic/p2p/geo_patch.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -29,68 +29,34 @@ defmodule ArchEthic.P2P.GeoPatch do
end

defp compute_patch(lat, lon) do
lat_sign = sign(lat)
lon_sign = sign(lon)
lat_pos = (lat + 90) / 11.25
lon_pos = (lon + 180) / 22.5
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@I-Archer-Zero
Looks like added 90,180 to avoid negative sign but look at

lat_pos

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It must be
lat_pos = (lat + 90) / 22.5

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@Neylix Neylix Mar 30, 2022 •
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Hi !
Dividing lat by 22.5 will have a result between 0 and 8. But we are looking for a range between 0 and 16 to get all hexadecimal possibilities (0 to F).
So we have to divide by 11.25 to get it.

I think on issue's example there is a mismatch. On the graph, latitude only have 8 parts, but on explication bellow it says that first 2 digits are on range of 0 to F so 16 parts...

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@I-Archer-Zero

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@internet-zero internet-zero Mar 30, 2022 •
edited
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Hi @Neylix (Cc @samuel-uniris)
Good observation!

lat should be divided by 22.5 and not 11.25 because we need square patches (not rectangle)
This also means that the lat/22.5 will have a result between 0 to 8

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Hi ! Thanks for your return.
I didn't know it had to be a square, I'll update it as you requested. Also need to add 4 to result to get index from C to 3 as in your graph.
I also noticed that in issue you say that first digit is for longitude index, but I did latitude first, should I update it too ?
I'm actually out of my PC until sunday, I'll update it at this time.

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Hello !
I fixed calculation in lastest commits

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I would suggest you can you >= and <= condition checks and fix the edge cases and also implement the algo as mentioned in #253. So, first digit and third digt can be [8,9,A,B,C,D,E,F,0,1,2,3,4,5,6,7] And second digit can be [C,D,E,F,0,1,2,3]

As precision digit being computed as per previous implementation.


fdc = [lat / 90, lon / 180]
first_digit = main_index_patch(trunc(lat_pos))
second_digit = main_index_patch(trunc(lon_pos))

sd =
[(lat - lat_sign * 45) / 2, (lon - lon_sign * 90) / 2]
|> resolve_with_sign([lat, lon])
lat_precision = ((lat_pos - trunc(lat_pos)) / 0.25) |> trunc()
lon_precision = ((lon_pos - trunc(lon_pos)) / 0.25) |> trunc()

sdc = [List.first(sd) / 22.5, List.last(sd) / 45]
third_digit = precision_index_patch(lat_precision, lon_precision)

td =
[
(List.first(sd) - lat_sign * 11.25) / 2,
(List.last(sd) - lon_sign * 22.5) / 2
]
|> resolve_with_sign(sd)

tdc = [List.first(td) / 5.625, List.last(td) / 11.25]

patch =
[index_patch(fdc), index_patch(sdc), index_patch(tdc)]
|> Enum.join("")

patch
[first_digit, second_digit, third_digit]
|> Enum.join("")
end

defp index_patch([f_i, s_i]) when f_i > 0.5 and f_i <= 1 and s_i < -0.5 and s_i >= -1, do: '0'
defp index_patch([f_i, s_i]) when f_i > 0.5 and f_i <= 1 and s_i < 0 and s_i >= -0.5, do: '1'
defp index_patch([f_i, s_i]) when f_i > 0.5 and f_i <= 1 and s_i < 0.5 and s_i >= 0, do: '2'
defp index_patch([f_i, s_i]) when f_i > 0.5 and f_i <= 1 and s_i < 1 and s_i >= 0.5, do: '3'

defp index_patch([f_i, s_i]) when f_i > 0 and f_i <= 0.5 and s_i < -0.5 and s_i >= -1, do: '4'
defp index_patch([f_i, s_i]) when f_i > 0 and f_i <= 0.5 and s_i < 0 and s_i >= -0.5, do: '5'
defp index_patch([f_i, s_i]) when f_i > 0 and f_i <= 0.5 and s_i < 0.5 and s_i >= 0, do: '6'
defp index_patch([f_i, s_i]) when f_i > 0 and f_i <= 0.5 and s_i < 1 and s_i >= 0.5, do: '7'

defp index_patch([f_i, s_i]) when f_i > -0.5 and f_i <= 0 and s_i < -0.5 and s_i >= -1, do: '8'
defp index_patch([f_i, s_i]) when f_i > -0.5 and f_i <= 0 and s_i < 0 and s_i >= -0.5, do: '9'
defp index_patch([f_i, s_i]) when f_i > -0.5 and f_i <= 0 and s_i < 0.5 and s_i >= 0, do: 'A'
defp index_patch([f_i, s_i]) when f_i > -0.5 and f_i <= 0 and s_i < 1 and s_i >= 0.5, do: 'B'

defp index_patch([f_i, s_i]) when f_i > -1 and f_i <= -0.5 and s_i < -0.5 and s_i >= -1, do: 'C'
defp index_patch([f_i, s_i]) when f_i > -1 and f_i <= -0.5 and s_i < 0 and s_i >= -0.5, do: 'D'
defp index_patch([f_i, s_i]) when f_i > -1 and f_i <= -0.5 and s_i < 0.5 and s_i >= 0, do: 'E'
defp index_patch([f_i, s_i]) when f_i > -1 and f_i <= -0.5 and s_i < 1 and s_i >= 0.5, do: 'F'

defp sign(number) when number < 0, do: -1
defp sign(number) when number >= 0, do: 1
defp main_index_patch(index) do
['8', '9', 'A', 'B', 'C', 'D', 'E', 'F', '0', '1', '2', '3', '4', '5', '6', '7']
|> Enum.at(index)
end

defp resolve_with_sign([first, second], [first2, second2]) do
defp precision_index_patch(index1, index2) do
[
do_resolve_with_sign(first, first2),
do_resolve_with_sign(second, second2)
['0', '1', '2', '3'],
['4', '5', '6', '7'],
['8', '9', 'A', 'B'],
['C', 'D', 'E', 'F']
]
end

defp do_resolve_with_sign(x1, x2) do
if sign(x1) == sign(x2) do
x1
else
x2 / 2
end
|> Enum.at(index1)
|> Enum.at(index2)
end
end
13 changes: 9 additions & 4 deletions test/archethic/p2p/geo_patch_test.exs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,9 @@
defmodule ArchEthic.P2P.GeoPatchTest do
@moduledoc """
This module defines the test case to be used by
geopatch tests.
"""

use ExUnit.Case

alias ArchEthic.P2P.GeoPatch
Expand Down Expand Up @@ -26,9 +31,9 @@ defmodule ArchEthic.P2P.GeoPatchTest do
end
end)

assert "511" == GeoPatch.from_ip({88, 22, 30, 229})
assert "500" == GeoPatch.from_ip({161, 235, 112, 33})
assert "410" == GeoPatch.from_ip({15, 62, 246, 57})
assert "266" == GeoPatch.from_ip({109, 164, 214, 168})
assert "3F7" == GeoPatch.from_ip({88, 22, 30, 229})
assert "3C9" == GeoPatch.from_ip({161, 235, 112, 33})
assert "3A6" == GeoPatch.from_ip({15, 62, 246, 57})
assert "401" == GeoPatch.from_ip({109, 164, 214, 168})
end
end