Make distance metric configurable; fix building period bug

src/graph/build.jl

@@ -40,7 +40,6 @@ function build_graph(instance::Instance)::Graph
     end
 
     # Build arcs from collection centers to plants, and from one plant to another
-    metric = _KnnDrivingDistance()
     for source in [collection_shipping_nodes; plant_shipping_nodes]
         for dest in process_nodes_by_input_product[source.product]
             distance = _calculate_distance(
@@ -48,7 +47,7 @@ function build_graph(instance::Instance)::Graph
                 source.location.longitude,
                 dest.location.latitude,
                 dest.location.longitude,
-                metric,
+                instance.distance_metric,
             )
             values = Dict("distance" => distance)
             arc = Arc(source, dest, values)

src/graph/dist.jl

@@ -6,19 +6,12 @@ using Geodesy
 using NearestNeighbors
 using DataFrames
 
-Base.@kwdef mutable struct _KnnDrivingDistance
-    tree = nothing
-    ratios = nothing
-end
-
-mutable struct _EuclideanDistance end
-
 function _calculate_distance(
     source_lat,
     source_lon,
     dest_lat,
     dest_lon,
-    ::_EuclideanDistance,
+    ::EuclideanDistance,
 )::Float64
     x = LLA(source_lat, source_lon, 0.0)
     y = LLA(dest_lat, dest_lon, 0.0)
@@ -30,7 +23,7 @@ function _calculate_distance(
     source_lon,
     dest_lat,
     dest_lon,
-    metric::_KnnDrivingDistance,
+    metric::KnnDrivingDistance,
 )::Float64
     if metric.tree === nothing
         basedir = joinpath(dirname(@__FILE__), "..", "..", "data")
@@ -54,13 +47,8 @@ function _calculate_distance(
     end
 
     # Compute Euclidean distance
-    dist_euclidean = _calculate_distance(
-        source_lat,
-        source_lon,
-        dest_lat,
-        dest_lon,
-        _EuclideanDistance(),
-    )
+    dist_euclidean =
+        _calculate_distance(source_lat, source_lon, dest_lat, dest_lon, EuclideanDistance())
 
     # Predict ratio
     idxs, _ = knn(metric.tree, [source_lat, source_lon, dest_lat, dest_lon], 5)

src/instance/parse.jl

@@ -23,10 +23,23 @@ function parse(json)::Instance
     validate(json, Schema(json_schema))
 
     building_period = [1]
-    if "building period (years)" in keys(json)
-        building_period = json["building period (years)"]
+    if "building period (years)" in keys(json["parameters"])
+        building_period = json["parameters"]["building period (years)"]
     end
 
+    distance_metric = EuclideanDistance()
+    if "distance metric" in keys(json["parameters"])
+        metric_name = json["parameters"]["distance metric"]
+        if metric_name == "driving"
+            distance_metric = KnnDrivingDistance()
+        elseif metric_name == "Euclidean"
+            # nop
+        else
+            error("Unknown distance metric: $metric_name")
+        end
+    end
+    @show distance_metric
+
     plants = Plant[]
     products = Product[]
     collection_centers = CollectionCenter[]
@@ -176,5 +189,12 @@ function parse(json)::Instance
     @info @sprintf("%12d collection centers", length(collection_centers))
     @info @sprintf("%12d candidate plant locations", length(plants))
 
-    return Instance(T, products, collection_centers, plants, building_period)
+    return Instance(
+        T,
+        products,
+        collection_centers,
+        plants,
+        building_period,
+        distance_metric,
+    )
 end

src/instance/structs.jl

@@ -48,10 +48,21 @@ mutable struct Plant
     storage_cost::Vector{Float64}
 end
 
+
+abstract type DistanceMetric end
+
+Base.@kwdef mutable struct KnnDrivingDistance <: DistanceMetric
+    tree = nothing
+    ratios = nothing
+end
+
+mutable struct EuclideanDistance <: DistanceMetric end
+
 mutable struct Instance
     time::Int64
     products::Vector{Product}
     collection_centers::Vector{CollectionCenter}
     plants::Vector{Plant}
     building_period::Vector{Int64}
+    distance_metric::DistanceMetric
 end

src/schemas/input.json

@@ -14,6 +14,9 @@
             "properties": {
                 "time horizon (years)": {
                     "type": "number"
+                },
+                "distance metric": {
+                    "type": "string"
                 }
             },
             "required": [