Graham McIntire
5a9359191f
Eliminates the external wgrib2 C tool dependency that blocked HRRR processing. Implements Lambert Conformal projection, simple packing (Template 5.0), complex packing with spatial differencing (Template 5.3), and GRIB2 section parsing — enough to extract point values from HRRR grid data using only Elixir.
95 lines
3 KiB
Elixir
95 lines
3 KiB
Elixir
defmodule Microwaveprop.Weather.Grib2.ComplexPackingTest do
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use ExUnit.Case, async: true
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alias Microwaveprop.Weather.Grib2.ComplexPacking
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alias Microwaveprop.Weather.Grib2.Section
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@fixture_path "test/fixtures/grib2/hrrr_tmp_2m.grib2"
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describe "extract_value/3 with real HRRR fixture" do
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@tag :fixture
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test "extracts a temperature value within meteorological range" do
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if File.exists?(@fixture_path) do
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fixture = File.read!(@fixture_path)
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{:ok, parsed} = Section.parse_message(fixture)
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# First grid point (index 0)
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{:ok, value} =
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ComplexPacking.extract_value(parsed.packing_params, parsed.data, 0)
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# Should be a temperature in Kelvin (roughly 200-340K)
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assert value > 200.0 and value < 340.0,
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"Expected temperature 200-340K, got #{value}"
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else
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IO.puts("Skipping fixture test — #{@fixture_path} not found")
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:ok
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end
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end
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@tag :fixture
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test "extracts values at multiple indices" do
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if File.exists?(@fixture_path) do
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fixture = File.read!(@fixture_path)
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{:ok, parsed} = Section.parse_message(fixture)
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# Check several indices across the grid
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for idx <- [0, 1000, 100_000, 500_000, 1_000_000, 1_905_140] do
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{:ok, value} =
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ComplexPacking.extract_value(parsed.packing_params, parsed.data, idx)
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assert value > 200.0 and value < 340.0,
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"Index #{idx}: expected 200-340K, got #{value}"
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end
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else
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:ok
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end
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end
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@tag :fixture
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test "Dallas area temperature is reasonable for a US city" do
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if File.exists?(@fixture_path) do
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fixture = File.read!(@fixture_path)
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{:ok, parsed} = Section.parse_message(fixture)
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grid = parsed.grid_params
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{:ok, {i, j}} = Microwaveprop.Weather.Grib2.LambertConformal.to_grid_index(grid, 32.78, -96.8)
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index = j * grid.nx + i
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{:ok, value} =
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ComplexPacking.extract_value(parsed.packing_params, parsed.data, index)
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# Dallas in March — Kelvin should be roughly 270-310K (roughly -3C to 37C)
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temp_c = value - 273.15
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assert temp_c > -10.0 and temp_c < 45.0,
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"Dallas temp #{Float.round(temp_c, 1)}C seems unreasonable"
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else
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:ok
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end
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end
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end
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describe "decode_all/2" do
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@tag :fixture
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test "decodes all values from fixture" do
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if File.exists?(@fixture_path) do
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fixture = File.read!(@fixture_path)
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{:ok, parsed} = Section.parse_message(fixture)
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{:ok, values_arr} = ComplexPacking.decode_all(parsed.packing_params, parsed.data)
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assert :array.size(values_arr) == parsed.packing_params.num_data_points
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# Check a sample of values are in reasonable temperature range
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for idx <- [0, 100_000, 500_000, 1_000_000, 1_905_140] do
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val = :array.get(idx, values_arr)
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assert val > 200.0 and val < 340.0,
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"Index #{idx}: expected 200-340K, got #{val}"
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end
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else
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:ok
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end
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end
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end
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end
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