From 4d03c91bc82dbfdd56878d25235ab4a034f01a73 Mon Sep 17 00:00:00 2001
From: Robert Lupton the Good <rhl@astro.princeton.edu>
Date: Mon, 17 Jun 2024 16:29:21 -1000
Subject: [PATCH 1/2] Treat all NaNs as equivalent in magnitude arrays

---
 python/pfs/drp/stella/coaddSpectra.py | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/python/pfs/drp/stella/coaddSpectra.py b/python/pfs/drp/stella/coaddSpectra.py
index bad9a2cc6..fcd9ce475 100644
--- a/python/pfs/drp/stella/coaddSpectra.py
+++ b/python/pfs/drp/stella/coaddSpectra.py
@@ -33,6 +33,21 @@
 __all__ = ("CoaddSpectraConfig", "CoaddSpectraTask")
 
 
+class SetWithNaN(set):
+    """A set which includes at most one NaN, despite the fact that NaN != NaN"""
+    def __init__(self, iterable):
+        """Construct a set from iterable with at most one NaN"""
+        sawNaN = False
+
+        for x in iterable:
+            if np.isnan(x):
+                if not sawNaN:
+                    self.add(x)
+                    sawNaN = True
+            else:
+                self.add(x)
+
+
 class CoaddSpectraConnections(
     PipelineTaskConnections,
     dimensions=("instrument", "skymap", "tract", "patch"),
@@ -289,7 +304,7 @@ def getTarget(self, target: Target, pfsConfigList: List[PfsConfig]) -> Target:
             for ff, flux in zip(pfsConfig.filterNames[0], pfsConfig.fiberFlux[0]):
                 fiberFlux[ff].append(flux)
         for ff in fiberFlux:
-            flux = set(fiberFlux[ff])
+            flux = SetWithNaN(fiberFlux[ff])
             if len(flux) > 1:
                 self.log.warn("Multiple %s flux for target %s (%s); using average" % (ff, target, flux))
                 flux = np.average(np.array(fiberFlux[ff]))

From e6252cd1e01a39ca23eea46fce2e0a4eb3a8f9cf Mon Sep 17 00:00:00 2001
From: Robert Lupton the Good <rhl@astro.princeton.edu>
Date: Tue, 18 Jun 2024 09:42:08 -1000
Subject: [PATCH 2/2] Redo SetWithNaN to avoid methods which circumvent
 protections

---
 python/pfs/drp/stella/coaddSpectra.py | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/python/pfs/drp/stella/coaddSpectra.py b/python/pfs/drp/stella/coaddSpectra.py
index fcd9ce475..ac6ded30a 100644
--- a/python/pfs/drp/stella/coaddSpectra.py
+++ b/python/pfs/drp/stella/coaddSpectra.py
@@ -33,20 +33,37 @@
 __all__ = ("CoaddSpectraConfig", "CoaddSpectraTask")
 
 
-class SetWithNaN(set):
-    """A set which includes at most one NaN, despite the fact that NaN != NaN"""
+class SetWithNaN:
+    """A subset of set which includes at most one NaN, despite the fact that NaN != NaN"""
+
     def __init__(self, iterable):
         """Construct a set from iterable with at most one NaN"""
+        self.__set = set()
         sawNaN = False
 
         for x in iterable:
             if np.isnan(x):
                 if not sawNaN:
-                    self.add(x)
+                    self.__set.add(x)
                     sawNaN = True
             else:
                 self.add(x)
 
+    def add(self, val):
+        if np.isnan(val) and np.isnan(list(self)).any():
+            return
+
+        self.__set.add(val)
+
+    def __len__(self):
+        return self.__set.__len__()
+
+    def __repr__(self):
+        return self.__set.__repr__()
+
+    def pop(self):
+        return self.__set.pop()
+
 
 class CoaddSpectraConnections(
     PipelineTaskConnections,