Implement lazy caching in SpectraAxis for looking up a spectrum value.

Refs #9435

Code/Mantid/Framework/API/inc/MantidAPI/NumericAxis.h

@@ -46,6 +46,9 @@ class MatrixWorkspace;
 class MANTID_API_DLL NumericAxis: public Axis
 {
 public:
+  /// Find the index of the value in the given set of edges
+  static size_t indexOfValue(const double value, const std::vector<double> & edges);
+
   NumericAxis(const std::size_t& length);
   NumericAxis(const std::vector<double>& centres);
   virtual ~NumericAxis(){}
@@ -75,8 +78,6 @@ class MANTID_API_DLL NumericAxis: public Axis
   /// Default constructor
   NumericAxis();
 
-  /// Find the index of the value in the given set of edges
-  size_t indexOfValue(const double value, const std::vector<double> & edges) const;
   /// A vector holding the centre values.
   std::vector<double> m_values;
 

Code/Mantid/Framework/API/inc/MantidAPI/SpectraAxis.h

@@ -77,8 +77,8 @@ class MANTID_API_DLL SpectraAxis: public Axis
   const SpectraAxis& operator=(const SpectraAxis&);
   /// A pointer to the workspace holding the axis
   const MatrixWorkspace* const m_parentWS;
-  /// Effective bin width
-  double m_halfBinWidth;
+  /// List of edge values for quick searching of values as if this is binned data
+  mutable std::vector<double> m_edges;
 };
 
 } // namespace API

Code/Mantid/Framework/API/src/NumericAxis.cpp

@@ -12,6 +12,40 @@ namespace Mantid
 namespace API
 {
 
+//------------------------------------------------------------------------------
+// static members
+//------------------------------------------------------------------------------
+
+/**
+ * @param value A value to find in a bin
+ * @param edges A list of edges that define the bins
+ * @return The index of the bin holding the value
+ */
+size_t NumericAxis::indexOfValue(const double value, const std::vector<double> &edges)
+{
+  if(value < edges.front())
+  {
+    throw std::out_of_range("NumericAxis::indexOfValue() - Input lower than first value.");
+  }
+  auto it = std::lower_bound(edges.begin(), edges.end(), value);
+  if (it == edges.end())
+  {
+    // Out of range
+    throw std::out_of_range("NumericAxis::indexOfValue() - Input value out of range");
+  }
+  // index of closest edge above value is distance of iterator from start
+  size_t edgeIndex = std::distance(edges.begin(), it);
+  // index of bin centre is one less since the first boundary offsets the whole range
+  // need to protect for case where value equals lowest bin boundary as that will return &
+  // not 1
+  if(edgeIndex > 0) return edgeIndex - 1;
+  else return edgeIndex;
+}
+
+//------------------------------------------------------------------------------
+// public members
+//------------------------------------------------------------------------------
+
 /** Constructor
  * @param length size of the numeric axis
  */
@@ -155,31 +189,5 @@ NumericAxis::NumericAxis()
 {
 }
 
-/**
- * @param value A value to find in a bin
- * @param edges A list of edges that define the bins
- * @return The index of the bin holding the value
- */
-size_t NumericAxis::indexOfValue(const double value, const std::vector<double> &edges) const
-{
-  if(value < edges.front())
-  {
-    throw std::out_of_range("NumericAxis::indexOfValue() - Input lower than first value.");
-  }
-  auto it = std::lower_bound(edges.begin(), edges.end(), value);
-  if (it == edges.end())
-  {
-    // Out of range
-    throw std::out_of_range("NumericAxis::indexOfValue() - Input value out of range");
-  }
-  // index of closest edge above value is distance of iterator from start
-  size_t edgeIndex = std::distance(edges.begin(), it);
-  // index of bin centre is one less since the first boundary offsets the whole range
-  // need to protect for case where value equals lowest bin boundary as that will return &
-  // not 1
-  if(edgeIndex > 0) return edgeIndex - 1;
-  else return edgeIndex;
-}
-
 } // namespace API
 } // namespace Mantid

Code/Mantid/Framework/API/src/SpectraAxis.cpp

@@ -3,6 +3,7 @@
 //----------------------------------------------------------------------
 #include "MantidAPI/SpectraAxis.h"
 #include "MantidAPI/MatrixWorkspace.h"
+#include "MantidAPI/NumericAxis.h"
 #include "MantidKernel/MultiThreaded.h"
 #include "MantidKernel/Exception.h"
 #include "MantidKernel/Unit.h"
@@ -21,10 +22,9 @@ using std::size_t;
  *  @param parentWorkspace The workspace to which this axis belongs
  */
 SpectraAxis::SpectraAxis(const MatrixWorkspace* const parentWorkspace)
-  : Axis(), m_parentWS(parentWorkspace), m_halfBinWidth(0.5)
+  : Axis(), m_parentWS(parentWorkspace), m_edges()
 {
   this->unit() = boost::make_shared<Kernel::Units::Label>("Spectrum", "");
-  m_halfBinWidth = 0.5*(this->getMax() - this->getMin())/static_cast<double>(m_parentWS->getNumberHistograms()-1);
 }
 
 /** Virtual constructor
@@ -94,36 +94,21 @@ void SpectraAxis::setValue(const std::size_t& index, const double& value)
  */
 size_t SpectraAxis::indexOfValue(const double value) const
 {
-  // try and be smart about how we find this. Most of the time
-  // the index & value don't differ by much. Start at a value
-  // slightly lower, 2 back, then the actual value so that most cases
-  // it should find it in a few jumps.
-  const size_t nspectra = m_parentWS->getNumberHistograms();
-  const auto & parentWS = *m_parentWS; // avoid constant dereference
-
-  size_t guess = (value > 2.0) ? static_cast<size_t>(value - 2.0) : 0;
-  if(guess >= nspectra) guess = nspectra/2; // start in the middle
-
-  size_t index(guess);
-  do
+  if(m_edges.empty()) //lazy-instantiation
   {
-    try
+    m_edges.resize(m_parentWS->getNumberHistograms() + 1);
+    const size_t npts = m_edges.size() - 1;
+    for( size_t i = 0; i < npts - 1; ++i )
     {
-      double curNo = static_cast<double>(parentWS.getSpectrum(index)->getSpectrumNo());
-      if((curNo - m_halfBinWidth <= value) && (value < curNo + m_halfBinWidth)) // creates an effective binning
-        return index;
+      m_edges[i+1] = 0.5*(this->getValue(i) + this->getValue(i+1));
     }
-    catch(std::range_error&)
-    {
-      continue;
-    }
-    ++index;
-    if(index == nspectra) index = 0; //wrap around to search everythin
-  }
-  while (index != guess);
+    // ends
+    m_edges[0] = this->getValue(0) - (m_edges[1] - this->getValue(0));
+    m_edges[npts] = this->getValue(npts-1) +
+                     (this->getValue(npts-1) - m_edges[npts-1]);
 
-  // Not found if we reached here
-  throw std::out_of_range("SpectraAxis::indexOfValue() - Value not found on axis");
+  }
+  return NumericAxis::indexOfValue(value, m_edges);
 }
 
 /** Returns the spectrum number at the position given (Spectra axis only)

Code/Mantid/Framework/API/test/SpectraAxisTest.h

@@ -114,9 +114,18 @@ class SpectraAxisTest : public CxxTest::TestSuite
   {
     for (int i=1; i < 6; ++i)
     {
-      TS_ASSERT_EQUALS(i-1, spectraAxis->indexOfValue(static_cast<double>(i - 0.5)) ); //lower boundary considered in this bin
+      // centre in this bin
       TS_ASSERT_EQUALS(i-1, spectraAxis->indexOfValue(static_cast<double>(i)) );
-      TS_ASSERT_EQUALS(i-1, spectraAxis->indexOfValue(static_cast<double>(i + 0.49)) );
+      //value on lower boundary in bin below with exception of first boundary where it is above
+      if(i==1)
+      {
+        TS_ASSERT_EQUALS(i-1, spectraAxis->indexOfValue(static_cast<double>(i - 0.5)));
+      }
+      else
+      {
+        TS_ASSERT_EQUALS(i-2, spectraAxis->indexOfValue(static_cast<double>(i - 0.5)) );
+      }
+      TS_ASSERT_EQUALS(i-1, spectraAxis->indexOfValue(static_cast<double>(i + 0.5)) );
     }
   }
 

Code/Mantid/Framework/DataHandling/test/SaveSPETest.h

@@ -177,14 +177,6 @@ class SaveSPETest : public CxxTest::TestSuite
   MatrixWorkspace_sptr setUpWorkspace(const std::string & input, MatrixWorkspace_sptr inputWS)
   {
     inputWS->getAxis(0)->unit() = Mantid::Kernel::UnitFactory::Instance().create("DeltaE");
-
-    // the following is largely about associating detectors with the workspace
-    for (int j = 0; j < NHIST; ++j)
-    {
-      // Just set the spectrum number to match the index
-      inputWS->getAxis(1)->setValue(j, j+1);
-    }
-
     AnalysisDataService::Instance().add(input,inputWS);
 
     // Load the instrument data

Code/Mantid/Framework/DataObjects/src/Workspace2D.cpp

@@ -53,9 +53,6 @@ namespace Mantid
     {
       m_noVectors = NVectors;
       data.resize(m_noVectors);
-      m_axes.resize(2);
-      m_axes[0] = new API::RefAxis(XLength, this);
-      m_axes[1] = new API::SpectraAxis(this);
 
       MantidVecPtr t1,t2;
       t1.access().resize(XLength); //this call initializes array to zero
@@ -74,6 +71,12 @@ namespace Mantid
         spec->setSpectrumNo(specid_t(i+1));
         spec->setDetectorID(detid_t(i+1));
       }
+
+      // Add axes that reference the data
+      m_axes.resize(2);
+      m_axes[0] = new API::RefAxis(XLength, this);
+      m_axes[1] = new API::SpectraAxis(this);
+
     }