Use pandas to check for duplicates

src/fmu/tools/sensitivities/_excel2dict.py

@@ -147,18 +147,15 @@ def _find_onebyone_input_sheet(input_filename):
 
 def _check_designinput(dsgn_input):
     """Checks for valid input in designinput sheet"""
-
     # Check for duplicate sensnames
-    sensitivity_names = []
-    for row in dsgn_input.itertuples():
-        if _has_value(row.sensname):
-            if row.sensname in sensitivity_names:
-                raise ValueError(
-                    "sensname '{}' was found on more than one row in designinput "
-                    "sheet. Two sensitivities can not share the same sensname. "
-                    "Please correct this and rerun".format(row.sensname)
-                )
-            sensitivity_names.append(row.sensname)
+    duplicates = dsgn_input[dsgn_input["sensname"].notna()]["sensname"].duplicated()
+    if duplicates.any():
+        duplicate_names = dsgn_input.loc[duplicates, "sensname"].values
+        raise ValueError(
+            f"sensname '{duplicate_names[0]}' was found on more than one row in "
+            f"designinput sheet. Two sensitivities can not share the same "
+            f"sensname. Please correct this and rerun"
+        )
 
 
 def _check_for_mixed_sensitivities(sens_name, sens_group):