Avoid supplying workspace to total_scattering function

This is to match other isis_powder style functions (e.g. create_vanadium and focus)

Given the nature of it being post reduction analysis, it might be worth adding the ability to provide a workspace.
This would have to be discussed with an instrument scientist to see if it of use.

Refs #21294

scripts/Diffraction/isis_powder/polaris.py

@@ -44,9 +44,11 @@ class Polaris(AbstractInst):
 
     def create_total_scattering_pdf(self, **kwargs):
         self._inst_settings.update_attributes(kwargs=kwargs)
-        # Validate that required files exist
-        # generate pdf
-        pdf_output = polaris_algs.generate_ts_pdf(focused_ws=self._inst_settings.focused_ws,
+        # Generate pdf
+        run_details = self._get_run_details(self._inst_settings.run_number)
+        focus_file_path = self._generate_out_file_paths(run_details)["nxs_filename"]
+        pdf_output = polaris_algs.generate_ts_pdf(run_number=self._inst_settings.run_number,
+                                                  focus_file_path=focus_file_path,
                                                   merge_banks=self._inst_settings.merge_banks)
         return pdf_output
 

scripts/Diffraction/isis_powder/polaris_routines/polaris_algs.py

@@ -76,8 +76,9 @@ def save_unsplined_vanadium(vanadium_ws, output_path):
     mantid.DeleteWorkspace(converted_group)
 
 
-def generate_ts_pdf(focused_ws, merge_banks=False):
-    pdf_output = mantid.ConvertUnits(InputWorkspace=focused_ws, Target="MomentumTransfer")
+def generate_ts_pdf(run_number, focus_file_path, merge_banks=False):
+    focused_ws = _obtain_focused_run(run_number, focus_file_path)
+    pdf_output = mantid.ConvertUnits(InputWorkspace=focused_ws.getName(), Target="MomentumTransfer")
     if merge_banks:
         raise RuntimeError("Merging banks is currently not supported")
     pdf_output = mantid.PDFFourierTransform(Inputworkspace=pdf_output, InputSofQType="S(Q)", PDFType="G(r)",
@@ -85,6 +86,32 @@ def generate_ts_pdf(focused_ws, merge_banks=False):
     return pdf_output
 
 
+def _obtain_focused_run(run_number, focus_file_path):
+    """
+    Searches for the focused workspace to use (based on user specified run number) in the ADS and then the output
+    directory.
+    If unsuccessful, a ValueError exception is thrown.
+    :param run_number: The run number to search for.
+    :param focus_file_path: The expected file path for the focused file.
+    :return: The focused workspace.
+    """
+    # Try the ADS first to avoid undesired loading
+    if mantid.mtd.doesExist('%s-Results-TOF-Grp' % run_number):
+        focused_ws = mantid.mtd['%s-Results-TOF-Grp' % run_number]
+    elif mantid.mtd.doesExist('%s-Results-D-Grp' % run_number):
+        focused_ws = mantid.mtd['%s-Results-D-Grp' % run_number]
+    else:
+        # Check output directory
+        print('No loaded focused files found. Searching in output directory...')
+        try:
+            focused_ws = mantid.LoadNexus(Filename=focus_file_path, OutputWorkspace='focused_ws').OutputWorkspace
+        except ValueError:
+            raise ValueError("Could not find focused file for run number:%s\n"
+                             "Please ensure a focused file has been produced and is located in the output directory."
+                             % run_number)
+    return focused_ws
+
+
 def _apply_bragg_peaks_masking(workspaces_to_mask, mask_list):
     output_workspaces = list(workspaces_to_mask)
 

scripts/Diffraction/isis_powder/polaris_routines/polaris_param_mapping.py

@@ -16,7 +16,6 @@ attr_mapping = \
      ParamMapEntry(ext_name="first_cycle_run_no",          int_name="run_in_range"),
      ParamMapEntry(ext_name="focused_cropping_values",     int_name="focused_cropping_values"),
      ParamMapEntry(ext_name="focused_bin_widths",          int_name="focused_bin_widths"),
-     ParamMapEntry(ext_name="focused_workspace",           int_name="focused_ws"),
      ParamMapEntry(ext_name="grouping_file_name",          int_name="grouping_file_name"),
      ParamMapEntry(ext_name="input_mode",                  int_name="input_mode", enum_class=INPUT_BATCHING),
      ParamMapEntry(ext_name="merge_banks",                 int_name="merge_banks"),