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Allow Goniometer to save Rotation Matrix directly to nexus file #39490

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Merged
merged 3 commits into from
Jun 24, 2025
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Merged

Allow Goniometer to save Rotation Matrix directly to nexus file #39490

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ef727ce
alter save and load to also handle r mat directly
andy-bridger Jun 16, 2025
ec2d9e9
add release note
andy-bridger Jun 16, 2025
f055d57
rename member variable to m_
andy-bridger Jun 18, 2025
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21 changes: 17 additions & 4 deletions Framework/Geometry/src/Instrument/Goniometer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -376,6 +376,10 @@ void Goniometer::saveNexus(::NeXus::File *file, const std::string &group) const
file->writeData("num_axes", int(motors.size()));
for (size_t i = 0; i < motors.size(); i++)
motors[i].saveNexus(file, "axis" + Strings::toString(i));
DblMatrix rMatrix = getR();
// Flatten DblMatrix for saving
std::vector<double> matrixData = rMatrix.getVector();
file->writeData("rotation_matrix", matrixData);
file->closeGroup();
}

Expand All @@ -390,10 +394,19 @@ void Goniometer::loadNexus(::NeXus::File *file, const std::string &group) {
file->readData("num_axes", num_axes);
motors.clear();
motors.reserve(num_axes);
for (int i = 0; i < num_axes; i++) {
GoniometerAxis newAxis;
newAxis.loadNexus(file, "axis" + Strings::toString(i));
motors.emplace_back(newAxis);
// If a rotation matrix is available and no rotation axes are provided load should behave like initFromR
if (file->hasData("rotation_matrix") && (num_axes < 1)) {
std::vector<double> matrixData;
file->readData("rotation_matrix", matrixData);
DblMatrix rotMat(matrixData);
setR(rotMat);
initFromR = true; // set as initFromR to prevent overwrite on R recalc
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Very minor -but I think the naming convention for such member variable (if that is the right term?) is m_initFromR - obviously this wasn't introduced in this PR (apologies for missing it before), but it helps to make the scope of the variable clear!

} else {
for (int i = 0; i < num_axes; i++) {
GoniometerAxis newAxis;
newAxis.loadNexus(file, "axis" + Strings::toString(i));
motors.emplace_back(newAxis);
}
}
file->closeGroup();
// Refresh cached values
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19 changes: 18 additions & 1 deletion Framework/Geometry/test/GoniometerTest.h
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Expand Up @@ -244,7 +244,7 @@ class GoniometerTest : public CxxTest::TestSuite {
}

/** Save and load to NXS file */
void test_nexus() {
void test_nexus_from_set_axes() {
NexusTestHelper th(true);
th.createFile("GoniometerTest.nxs");

Expand All @@ -264,6 +264,23 @@ class GoniometerTest : public CxxTest::TestSuite {
TS_ASSERT_EQUALS(G2.getR(), G.getR());
}

void test_nexus_from_set_matrix() {
NexusTestHelper th(true);
th.createFile("GoniometerTest2.nxs");

Mantid::Kernel::DblMatrix rotation_x{{1, 0, 0, 0, 0, -1, 0, 1, 0}}; // 90 degrees around x axis
Goniometer G(rotation_x);
TS_ASSERT_EQUALS(G.getR().equals(rotation_x), true);
G.saveNexus(th.file.get(), "goniometer");

// Reload from the file
th.reopenFile();
Goniometer G2;
G2.loadNexus(th.file.get(), "goniometer");
// Rotation matrices should be the same after loading
TS_ASSERT_EQUALS(G2.getR(), G.getR());
}

void test_equals_when_identical() {
Mantid::Kernel::DblMatrix rotation_x{{1, 0, 0, 0, 0, -1, 0, 1, 0}}; // 90 degrees around x axis
Goniometer a(rotation_x);
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1 change: 1 addition & 0 deletions docs/source/release/v6.13.0/Framework/Bugfixes/Used/39490.rst
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@@ -0,0 +1 @@
- ``saveNexus`` and ``loadNexus`` methods of :py:obj:`~mantid.geometry.Goniometer` object now directly save/load a copy of the rotation matrix. Previously, upon saving/loading, the :py:obj:`~mantid.geometry.Goniometer` would only deal with the rotation axes, leading to loss of rotation information if the :py:obj:`~mantid.geometry.Goniometer` had been defined using ``setR`` method, or similar approach.