BUG: fix collinearity message when instruments were manually specified

pyblp/economies/economy.py

@@ -163,7 +163,7 @@ def _format_formulations(self) -> str:
 
         return format_table(header, *data, title="Formulations")
 
-    def _detect_collinearity(self) -> None:
+    def _detect_collinearity(self, added_exogenous: bool) -> None:
         """Detect any collinearity issues in product data matrices."""
 
         # skip collinearity checking when it is disabled via zero tolerances
@@ -175,8 +175,8 @@ def _detect_collinearity(self) -> None:
             'X1': [str(f) for f in self._X1_formulations],
             'X2': [str(f) for f in self._X2_formulations],
             'X3': [str(f) for f in self._X3_formulations],
-            'ZD': [str(f) for f in self._X1_formulations if 'prices' not in f.names],
-            'ZS': [str(f) for f in self._X3_formulations]
+            'ZD': [str(f) for f in self._X1_formulations if 'prices' not in f.names] if added_exogenous else [],
+            'ZS': [str(f) for f in self._X3_formulations] if added_exogenous else [],
         }
         matrix_labels.update({
             'ZD': [f'demand_instruments{i}' for i in range(self.MD - len(matrix_labels['ZD']))] + matrix_labels['ZD'],

pyblp/economies/problem.py

@@ -1346,7 +1346,7 @@ def __init__(
                 self._handle_errors(ZS_errors)
 
         # detect any problems with the product data
-        self._detect_collinearity()
+        self._detect_collinearity(add_exogenous)
 
         # output information about the initialized problem
         output(f"Initialized the problem after {format_seconds(time.time() - start_time)}.")
@@ -1406,7 +1406,7 @@ def __init__(self, problem: ProblemEconomy, demand_instruments: Array, supply_in
                 raise exceptions.MultipleErrors(ZS_errors)
 
         # detect any collinearity issues with the updated instruments
-        self._detect_collinearity()
+        self._detect_collinearity(added_exogenous=True)
 
         # output information about the re-created problem
         output(f"Re-created the problem after {format_seconds(time.time() - start_time)}.")