Merge pull request Pyomo#3061 from asifhaider/fix_logical_expressions

Remove incorrect use of identity (is) comparisons

pyomo/neos/plugins/NEOS.py

@@ -50,7 +50,7 @@ def create_command_line(self, executable, problem_files):
                 logger.info("Solver log file: '%s'" % (self._log_file,))
             if self._soln_file is not None:
                 logger.info("Solver solution file: '%s'" % (self._soln_file,))
-            if self._problem_files is not []:
+            if self._problem_files != []:
                 logger.info("Solver problem files: %s" % (self._problem_files,))
 
         return Bunch(cmd="", log_file=self._log_file, env="")

pyomo/opt/base/convert.py

@@ -55,7 +55,7 @@ def convert_problem(
         if os.sep in fname:  # pragma:nocover
             fname = tmp.split(os.sep)[-1]
         source_ptype = [guess_format(fname)]
-        if source_ptype is [None]:
+        if source_ptype == [None]:
             raise ConverterError("Unknown suffix type: " + tmp)
     else:
         source_ptype = args[0].valid_problem_types()

pyomo/opt/solver/shellcmd.py

@@ -260,7 +260,7 @@ def _apply_solver(self):
                 print("Solver log file: '%s'" % self._log_file)
             if self._soln_file is not None:
                 print("Solver solution file: '%s'" % self._soln_file)
-            if self._problem_files is not []:
+            if self._problem_files != []:
                 print("Solver problem files: %s" % str(self._problem_files))
 
         sys.stdout.flush()