From dd5641f3e2b129f8376b8bc16c26a7a0411e43b2 Mon Sep 17 00:00:00 2001
From: Lukas Kluft <lukas.kluft@gmail.com>
Date: Sun, 16 Feb 2025 11:06:27 +0100
Subject: [PATCH] Properly normalize remap weights after coarsening
For ocean grids, the re-scaling factor is not always 4, but determined
by the actual number of links to the destination address.
---
coarsen_weights.py | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/coarsen_weights.py b/coarsen_weights.py
index b84a22d..d619954 100755
--- a/coarsen_weights.py
+++ b/coarsen_weights.py
@@ -17,9 +17,14 @@ def coarsen_weight_file(inweights, outweights, nbisections=1):
w = weights[["src_address", "dst_address", "remap_matrix"]].to_dataframe()
w.dst_address = ((w.dst_address - 1) // coarsen) + 1
- w.remap_matrix = w.remap_matrix / coarsen
- new_w = w.groupby(["src_address", "dst_address"]).sum().reset_index()
+ # Normalize weights by actual number of links to new destination address
+ new_w = w.set_index("dst_address")
+ new_w["remap_matrix"] = new_w["remap_matrix"] / new_w["remap_matrix"].groupby("dst_address").count()
+ new_w = new_w.reset_index()
+
+ # Combine equivalent links into one
+ new_w = new_w.groupby(["src_address", "dst_address"]).sum().reset_index()
new_w.index.name = "num_links"
new_w = new_w.to_xarray()
--
GitLab