Define Regridder type

Project.toml

@@ -1,7 +1,7 @@
 name = "XESMF"
 uuid = "2e0b0046-e7a1-486f-88de-807ee8ffabe5"
 authors = ["NumericalEarth and contributors"]
-version = "0.1.1"
+version = "0.1.2"
 
 [deps]
 CondaPkg = "992eb4ea-22a4-4c89-a5bb-47a3300528ab"

src/XESMF.jl

@@ -4,29 +4,24 @@ using CondaPkg
 using PythonCall
 using SparseArrays
 
-# Placeholder (will be overwritten in __init__)
-xesmf = Py(nothing)
+struct Regridder{S, M, V1, V2}
+    method :: M
+    weights :: S
+    src_temp :: V1
+    dst_temp :: V2
+end
 
-function __init__()
-    global xesmf
-    try
-        xesmf = pyimport("xesmf")
-    catch e
-        if occursin("No module named 'ESMF'", string(e))
-            error("""
-            XESMF.jl requires the ESMF library to be installed.
-            This is usually handled automatically by CondaPkg, but on some systems
-            (particularly Windows) it may need to be installed manually.
+Base.summary(r::Regridder{S, M, V1, V2}) where {S, M, V1, V2} = "$(r.method) Regridder"
 
-            Try running:
-            julia -e "using CondaPkg; CondaPkg.add(["esmf", "esmpy"])"
-            """)
-        else
-            rethrow(e)
-        end
-    end
+function Base.show(io::IO, r::Regridder)
+    print(io, summary(r), '\n')
+    print(io, "├── weights: ", summary(r.weights), '\n')
+    print(io, "├── src_temp: ", summary(r.src_temp), '\n')
+    print(io, "└── dst_temp: ", summary(r.dst_temp))
 end
 
+function extract_xesmf_coordinates_structure end
+
 """
     sparse_regridder_weights(FT, regridder)
 
@@ -47,4 +42,73 @@ end
 
 sparse_regridder_weights(regridder) = sparse_regridder_weights(Float64, regridder)
 
+"""
+    Regridder(src_coordinates::Dict{String, <:AbstractArray},
+              dst_coordinates::Dict{String, <:AbstractArray};
+              method="conservative", periodic=false)
+
+Return a Regridder from the xESMF Python package to regrid data from
+`src_coordinates` to `dst_coordinates` using the specified `method`.
+
+The `src_coordinates` and `dst_coordinates` are dictionaries that contain
+information about the two grids.
+
+xESMF exposes five different regridding algorithms from the ESMF library,
+specified with the `method` keyword argument:
+
+* `"bilinear"`: `ESMF.RegridMethod.BILINEAR`
+* `"conservative"`: `ESMF.RegridMethod.CONSERVE`
+* `"conservative_normed"`: `ESMF.RegridMethod.CONSERVE`
+* `"patch"`: `ESMF.RegridMethod.PATCH`
+* `"nearest_s2d"`: `ESMF.RegridMethod.NEAREST_STOD`
+* `"nearest_d2s"`: `ESMF.RegridMethod.NEAREST_DTOS`
+
+where `conservative_normed` is just the conservative method with the normalization set to
+`ESMF.NormType.FRACAREA` instead of the default `norm_type = ESMF.NormType.DSTAREA`.
+
+For more information, see the Python xESMF documentation at:
+
+> https://xesmf.readthedocs.io/en/latest/notebooks/Compare_algorithms.html
+"""
+function Regridder(src_coordinates::Dict{String, <:AbstractArray},
+                   dst_coordinates::Dict{String, <:AbstractArray};
+                   method="conservative", periodic=false)
+
+    xesmf = XESMF.xesmf
+    regridder = xesmf.Regridder(src_coordinates, dst_coordinates, method; periodic)
+    method = uppercasefirst(string(regridder.method))
+
+    weights = XESMF.sparse_regridder_weights(regridder)
+
+    Ndst, Nsrc = size(weights)
+
+    temp_src = zeros(Nsrc)
+    temp_dst = zeros(Ndst)
+
+    return Regridder(method, weights, temp_src, temp_dst)
+end
+
+# Placeholder (will be overwritten in __init__)
+xesmf = Py(nothing)
+
+function __init__()
+    global xesmf
+    try
+        xesmf = pyimport("xesmf")
+    catch e
+        if occursin("No module named 'ESMF'", string(e))
+            error("""
+            XESMF.jl requires the ESMF library to be installed.
+            This is usually handled automatically by CondaPkg, but on some systems
+            (particularly Windows) it may need to be installed manually.
+
+            Try running:
+            julia -e "using CondaPkg; CondaPkg.add(["esmf", "esmpy"])"
+            """)
+        else
+            rethrow(e)
+        end
+    end
+end
+
 end # module XESMF