Tables.jl interface is confusing

Author: tpoisot

Project.toml

@@ -17,6 +17,7 @@ Revise = "295af30f-e4ad-537b-8983-00126c2a3abe"
 SimpleSDMDatasets = "2c7d61d0-5c73-410d-85b2-d2e7fbbdcefa"
 SimpleSDMLayers = "2c645270-77db-11e9-22c3-0f302a89c64c"
 StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
+Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 
 [compat]
 ArchGDAL = "0.9"

src/tables.jl

@@ -0,0 +1,37 @@
+# We are a Tables.jl provider
+Tables.istable(::Type{T}) where {T <: SimpleSDMLayer} = true
+
+# We access data in a layer by rows (they are provided by iteration)
+Tables.rowaccess(::Type{T}) where {T <: SimpleSDMLayer} = true
+
+# 
+function Tables.schema(layer::T) where {T <: SimpleSDMLayer}
+    lon_type = eltype(longitudes(layer))
+    lat_type = eltype(latitudes(layer))
+    elm_type = eltype(l)
+    colnames = [:longitude, :latitude, :value]
+    coltypes = [lon_type, lat_type, elm_type]
+    return Tables.schema(colnames, coltypes)
+end
+
+function Tables.rows(layer::T) where {T <: SimpleSDMLayer}
+    return layer
+end
+
+function Tables.getcolumn(row, i::Int)
+    if i == 1
+        return row.first[1]
+    elseif i == 2
+        return row.first[2]
+    end
+    return row.second
+end
+
+function Tables.getcolumn(row, nm::Symbol)
+    if nm == :longitude
+        return row.first[1]
+    elseif nm == :latitude
+        return row.first[2]
+    end
+    return row.second
+end