Merge pull request #38738 from rosswhitfield/fix_LoadErrorEventsNexus…

…_zero_events Fix LoadErrorEventsNexus/PulseIndexer when there are zero events
mantidproject · Jan 30, 2025 · cba714b · cba714b
2 parents 7cfebde + 2da9fbc
commit cba714b
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Showing 5 changed files with 41 additions and 4 deletions.
diff --git a/Framework/DataHandling/src/LoadErrorEventsNexus.cpp b/Framework/DataHandling/src/LoadErrorEventsNexus.cpp
@@ -132,7 +132,10 @@ void LoadErrorEventsNexus::exec() {
   g_log.information() << "Loaded " << numEvents << " events with TOF min = " << min_tof << ", max = " << max_tof
                       << "\n";
 
-  eventWS->setAllX(HistogramData::BinEdges{min_tof, max_tof});
+  if (min_tof < max_tof)
+    eventWS->setAllX(HistogramData::BinEdges{min_tof, max_tof});
+  else
+    eventWS->setAllX(HistogramData::BinEdges{0, 16666.7});
 
   outWS->getAxis(0)->setUnit("TOF");
   outWS->setYUnit("Counts");

diff --git a/Framework/DataHandling/src/PulseIndexer.cpp b/Framework/DataHandling/src/PulseIndexer.cpp
@@ -46,15 +46,15 @@ PulseIndexer::PulseIndexer(std::shared_ptr<std::vector<uint64_t>> event_index, c
   // determine if should trim the front end to remove empty pulses
   auto firstPulseIndex = m_roi.front();
   auto eventRange = this->getEventIndexRange(firstPulseIndex);
-  while (eventRange.first == eventRange.second) {
+  while (eventRange.first == eventRange.second && eventRange.first < m_numEvents) {
     ++firstPulseIndex;
     eventRange = this->getEventIndexRange(firstPulseIndex);
   }
 
   // determine if should trim the back end to remove empty pulses
   auto lastPulseIndex = m_roi.back();
   eventRange = this->getEventIndexRange(lastPulseIndex - 1);
-  while (eventRange.first == eventRange.second) {
+  while (eventRange.first == eventRange.second && eventRange.second > 0) {
     --lastPulseIndex;
     eventRange = this->getEventIndexRange(lastPulseIndex - 1);
   }
@@ -146,7 +146,7 @@ size_t PulseIndexer::getLastPulseIndex() const { return m_roi.back(); }
 std::pair<size_t, size_t> PulseIndexer::getEventIndexRange(const size_t pulseIndex) const {
   const auto start = this->getStartEventIndex(pulseIndex);
   // return early if the start is too big
-  if (start > m_numEvents)
+  if (start >= m_numEvents)
     return std::make_pair(start, m_numEvents);
 
   // get the end index

diff --git a/Framework/DataHandling/test/LoadErrorEventsNexusTest.h b/Framework/DataHandling/test/LoadErrorEventsNexusTest.h
@@ -74,6 +74,26 @@ class LoadErrorEventsNexusTest : public CxxTest::TestSuite {
     TS_ASSERT_EQUALS(events[0].pulseTime(), Mantid::Types::Core::DateAndTime("2021-10-06T14:25:29.962441733-04:00"))
   }
 
+  void test_CG3_zeroEvents() {
+    // This file contains no events in bank_error_events so should create an EventWorkspace with 0 events
+    LoadErrorEventsNexus alg;
+    alg.setChild(true);
+    TS_ASSERT_THROWS_NOTHING(alg.initialize())
+    TS_ASSERT(alg.isInitialized())
+    TS_ASSERT_THROWS_NOTHING(alg.setPropertyValue("OutputWorkspace", "unused"))
+    TS_ASSERT_THROWS_NOTHING(alg.setPropertyValue("Filename", "CG3_960.nxs.h5"))
+    TS_ASSERT(alg.execute());
+
+    Mantid::DataObjects::EventWorkspace_sptr outputWS = alg.getProperty("OutputWorkspace");
+    TS_ASSERT(outputWS);
+
+    TS_ASSERT_EQUALS(outputWS->blocksize(), 1)
+    TS_ASSERT_EQUALS(outputWS->getNumberHistograms(), 1)
+    TS_ASSERT_EQUALS(outputWS->getNumberEvents(), 0)
+    TS_ASSERT_EQUALS(outputWS->readX(0)[0], 0)
+    TS_ASSERT_DELTA(outputWS->readX(0)[1], 16666.7, 1e-9)
+  }
+
   void test_HYSA() {
     // this should fail to load as bank_error_events does not exist in this file
 

diff --git a/Framework/DataHandling/test/PulseIndexerTest.h b/Framework/DataHandling/test/PulseIndexerTest.h
@@ -169,6 +169,19 @@ class PulseIndexerTest : public CxxTest::TestSuite {
     run_test(eventIndices, start_event_index, total_events, first_pulse_index);
   }
 
+  void test_zerosEvents() {
+    // test that the pulse indexer can handle no events
+    auto eventIndices = std::make_shared<std::vector<uint64_t>>();
+    eventIndices->push_back(0);
+    eventIndices->push_back(0);
+
+    constexpr size_t start_event_index{0};
+    constexpr size_t total_events{0};
+    constexpr size_t first_pulse_index{1};
+
+    run_test(eventIndices, start_event_index, total_events, first_pulse_index);
+  }
+
   void test_invalidPulseROI() {
     auto eventIndices = generate_nonConstant();
 

diff --git a/docs/source/release/v6.12.0/Framework/Algorithms/Bugfixes/38738.rst b/docs/source/release/v6.12.0/Framework/Algorithms/Bugfixes/38738.rst
@@ -0,0 +1 @@
+- Fixed a bug in :ref:`LoadErrorEventsNexus <algm-LoadErrorEventsNexus>` that would cause it to hang when the error bank had zero events.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		- Fixed a bug in :ref:`LoadErrorEventsNexus <algm-LoadErrorEventsNexus>` that would cause it to hang when the error bank had zero events.