Re #21128. Add MatrixWorkspace::setMaskedBins.

To be used by ExtractSpectra2.

Framework/API/inc/MantidAPI/MatrixWorkspace.h

@@ -451,6 +451,7 @@ public:
   /// index, weight>
   typedef std::map<size_t, double> MaskList;
   const MaskList &maskedBins(const size_t &workspaceIndex) const;
+  void setMaskedBins(const size_t workspaceIndex, const MaskList &maskedBins);
 
   // Methods handling the internal monitor workspace
   virtual void

Framework/API/src/MatrixWorkspace.cpp

@@ -1084,6 +1084,16 @@ MatrixWorkspace::maskedBins(const size_t &workspaceIndex) const {
   return it->second;
 }
 
+/** Set the list of masked bins for given workspaceIndex. Not thread safe.
+ *
+ * No data is masked and previous masking for any bin for this workspace index
+ * is overridden, so this should only be used for copying flags into a new
+ * workspace, not for performing masking operations. */
+void MatrixWorkspace::setMaskedBins(const size_t workspaceIndex,
+                                    const MaskList &maskedBins) {
+  m_masks[workspaceIndex] = maskedBins;
+}
+
 /** Sets the internal monitor workspace to the provided workspace.
  *  This method is intended for use by data-loading algorithms.
  *  Note that no checking is performed as to whether this workspace actually

Framework/API/test/MatrixWorkspaceTest.h

@@ -742,6 +742,16 @@ public:
     }
   }
 
+  void testSetMaskedBins() {
+    auto ws = makeWorkspaceWithDetectors(2, 2);
+    ws->flagMasked(0, 1);
+    ws->flagMasked(1, 0);
+    ws->setMaskedBins(1, ws->maskedBins(0));
+    TS_ASSERT(ws->hasMaskedBins(1));
+    TS_ASSERT_EQUALS(ws->maskedBins(1).size(), 1);
+    TS_ASSERT_EQUALS(ws->maskedBins(0).begin()->first, 1);
+  }
+
   void testSize() {
     WorkspaceTester wkspace;
     wkspace.initialize(1, 4, 3);