python-control
diff --git a/‎control/flatsys/flatsys.py
Lines changed: 5 additions & 0 deletions b/‎control/flatsys/flatsys.py
Lines changed: 5 additions & 0 deletions
diff --git a/‎control/iosys.py
Lines changed: 10 additions & 1 deletion b/‎control/iosys.py
Lines changed: 10 additions & 1 deletion
diff --git a/‎control/namedio.py
Lines changed: 6 additions & 12 deletions b/‎control/namedio.py
Lines changed: 6 additions & 12 deletions
diff --git a/‎control/tests/namedio_test.py
Lines changed: 6 additions & 0 deletions b/‎control/tests/namedio_test.py
Lines changed: 6 additions & 0 deletions
@@ -156,6 +156,11 @@ def __init__(self,
 
         # Save the length of the flat flag
 
+    def __str__(self):
+        return f"{NonlinearIOSystem.__str__(self)}\n\n" \
+            + f"Forward: {self.forward}\n" \
+            + f"Reverse: {self.reverse}"
+
     def forward(self, x, u, params={}):
 
         """Compute the flat flag given the states and input.
 
@@ -706,6 +706,10 @@ def _out(self, t, x, u):
             + self.D @ np.reshape(u, (-1, 1))
         return np.array(y).reshape((-1,))
 
+    def __repr__(self):
+        # Need to define so that I/O system gets used instead of StateSpace
+        return InputOutputSystem.__repr__(self)
+
     def __str__(self):
         return InputOutputSystem.__str__(self) + "\n\n" \
             + StateSpace.__str__(self)
@@ -786,7 +790,7 @@ def __init__(self, updfcn, outfcn=None, inputs=None, outputs=None,
 
         # Initialize the rest of the structure
         dt = kwargs.pop('dt', config.defaults['control.default_dt'])
-        super(NonlinearIOSystem, self).__init__(
+        super().__init__(
             inputs=inputs, outputs=outputs, states=states,
             params=params, dt=dt, name=name
         )
@@ -816,6 +820,11 @@ def __init__(self, updfcn, outfcn=None, inputs=None, outputs=None,
         # Initialize current parameters to default parameters
         self._current_params = params.copy()
 
+    def __str__(self):
+        return f"{InputOutputSystem.__str__(self)}\n\n" + \
+            f"Update: {self.updfcn}\n" + \
+            f"Output: {self.outfcn}"
+
     # Return the value of a static nonlinear system
     def __call__(sys, u, params=None, squeeze=None):
         """Evaluate a (static) nonlinearity at a given input value
 
@@ -51,22 +51,16 @@ def __init__(
     nstates = None
 
     def __repr__(self):
-        return str(type(self)) + ": " + self.name if self.name is not None \
-            else str(type(self))
+        return f'<{self.__class__.__name__}:{self.name}:' + \
+            f'{list(self.input_labels)}->{list(self.output_labels)}>'
 
     def __str__(self):
         """String representation of an input/output object"""
-        str = "Object: " + (self.name if self.name else "(None)") + "\n"
-        str += "Inputs (%s): " % self.ninputs
-        for key in self.input_index:
-            str += key + ", "
-        str += "\nOutputs (%s): " % self.noutputs
-        for key in self.output_index:
-            str += key + ", "
+        str = f"<{self.__class__.__name__}>: {self.name}\n"
+        str += f"Inputs ({self.ninputs}): {self.input_labels}\n"
+        str += f"Outputs ({self.noutputs}): {self.output_labels}\n"
         if self.nstates is not None:
-            str += "\nStates (%s): " % self.nstates
-            for key in self.state_index:
-                str += key + ", "
+            str += f"States ({self.nstates}): {self.state_labels}"
         return str
 
     # Find a signal by name
 
@@ -31,6 +31,8 @@ def test_named_ss():
     assert sys.input_labels == ['u[0]', 'u[1]']
     assert sys.output_labels == ['y[0]', 'y[1]']
     assert sys.state_labels == ['x[0]', 'x[1]']
+    assert repr(sys) == \
+        "<LinearIOSystem:sys[0]:['u[0]', 'u[1]']->['y[0]', 'y[1]']>"
 
     # Pass the names as arguments
     sys = ct.ss(
@@ -41,6 +43,8 @@ def test_named_ss():
     assert sys.input_labels == ['u1', 'u2']
     assert sys.output_labels == ['y1', 'y2']
     assert sys.state_labels == ['x1', 'x2']
+    assert repr(sys) == \
+        "<LinearIOSystem:system:['u1', 'u2']->['y1', 'y2']>"
 
     # Do the same with rss
     sys = ct.rss(['x1', 'x2', 'x3'], ['y1', 'y2'], 'u1', name='random')
@@ -49,3 +53,5 @@ def test_named_ss():
     assert sys.input_labels == ['u1']
     assert sys.output_labels == ['y1', 'y2']
     assert sys.state_labels == ['x1', 'x2', 'x3']
+    assert repr(sys) == \
+        "<LinearIOSystem:random:['u1']->['y1', 'y2']>"