simplify rebin

CMB-S4 · Sep 20, 2023 · d9e356e · d9e356e
1 parent 3ff69d2
commit d9e356e
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Showing 3 changed files with 18 additions and 8 deletions.
diff --git a/maps/include/maps/HealpixSkyMapInfo.h b/maps/include/maps/HealpixSkyMapInfo.h
@@ -38,6 +38,8 @@ class HealpixSkyMapInfo : public G3FrameObject {
 	std::vector<double> PixelToAngle(size_t pixel) const;
 	size_t AngleToPixel(double alpha, double delta) const;
 
+	size_t RebinPixel(size_t pixel, size_t scale) const;
+
 	void GetRebinAngles(size_t pixel, size_t scale,
 	    std::vector<double> & alphas, std::vector<double> & deltas) const;
 

diff --git a/maps/src/HealpixSkyMap.cxx b/maps/src/HealpixSkyMap.cxx
@@ -1047,18 +1047,12 @@ G3SkyMapPtr HealpixSkyMap::Rebin(size_t scale, bool norm) const
 	else
 		return out;
 
-	const size_t scale2 = scale * scale;
-	const double sqscal = norm ? scale2 : 1.0;
+	const double sqscal = norm ? scale * scale : 1.0;
 
 	for (auto i : *this) {
 		if (i.second == 0)
 			continue;
-		ssize_t ip = i.first;
-		if (!nested())
-			ring2nest64(nside(), ip, &ip);
-		ip /= scale2;
-		if (!nested())
-			nest2ring64(out->nside(), ip, &ip);
+		size_t ip = info_.RebinPixel(i.first, scale);
 		(*out)[ip] += i.second / sqscal;
 	}
 

diff --git a/maps/src/HealpixSkyMapInfo.cxx b/maps/src/HealpixSkyMapInfo.cxx
@@ -258,6 +258,20 @@ HealpixSkyMapInfo::PixelToAngle(size_t pixel) const
 	return {alpha, delta};
 }
 
+size_t
+HealpixSkyMapInfo::RebinPixel(size_t pixel, size_t scale) const
+{
+	ssize_t pix = pixel;
+
+	if (!nested_)
+		ring2nest64(nside_, pix, &pix);
+	pix /= scale * scale;
+	if (!nested_)
+		nest2ring64(nside_ / scale, pix, &pix);
+
+	return pix;
+}
+
 void
 HealpixSkyMapInfo::GetRebinAngles(size_t pixel, size_t scale,
     std::vector<double> & alphas, std::vector<double> & deltas) const