fix up copying of signal names

murrayrm · murrayrm · commit a123f15c647e · 2022-12-17T07:29:37.000-08:00
diff --git a/control/statesp.py b/control/statesp.py
@@ -1521,7 +1521,6 @@ def output(self, t, x, u=None, params=None):
 
 
 # TODO: add discrete time check
-# TODO: copy signal names
 def _convert_to_statespace(sys):
     """Convert a system to state space form (if needed).
 
diff --git a/control/tests/xferfcn_test.py b/control/tests/xferfcn_test.py
@@ -8,7 +8,8 @@
 import operator
 
 import control as ct
-from control import StateSpace, TransferFunction, rss, ss2tf, evalfr
+from control import StateSpace, TransferFunction, rss, evalfr
+from control import ss, ss2tf, tf, tf2ss
 from control import isctime, isdtime, sample_system, defaults
 from control.statesp import _convert_to_statespace
 from control.xferfcn import _convert_to_transfer_function
@@ -1111,3 +1112,33 @@ def test_zpk(zeros, poles, gain, args, kwargs):
 
     if kwargs.get('name'):
         assert sys.name == kwargs.get('name')
+
+@pytest.mark.parametrize("sys, convert", [
+    (StateSpace([-1], [1], [1], [0]), ss2tf),
+    (StateSpace([-1], [1], [1], [0]), ss),
+    (StateSpace([-1], [1], [1], [0]), tf),
+    (StateSpace([-1], [1], [1], [0], inputs='in', outputs='out'), ss2tf),
+    (StateSpace([-1], [1], [1], [0], inputs=1, outputs=1), ss2tf),
+    (StateSpace([-1], [1], [1], [0], inputs='in', outputs='out'), ss),
+    (StateSpace([-1], [1], [1], [0], inputs='in', outputs='out'), tf),
+    (TransferFunction([1], [1, 1]), tf2ss),
+    (TransferFunction([1], [1, 1]), tf),
+    (TransferFunction([1], [1, 1]), ss),
+    (TransferFunction([1], [1, 1], inputs='in', outputs='out'), tf2ss),
+    (TransferFunction([1], [1, 1], inputs=1, outputs=1), tf2ss),
+    (TransferFunction([1], [1, 1], inputs='in', outputs='out'), tf),
+    (TransferFunction([1], [1, 1], inputs='in', outputs='out'), ss),
+])
+def test_copy_names(sys, convert):
+    # Convert a system with no renaming
+    cpy = convert(sys)
+
+    assert cpy.input_labels == sys.input_labels
+    assert cpy.input_labels == sys.input_labels
+    if cpy.nstates is not None and sys.nstates is not None:
+        assert cpy.state_labels == sys.state_labels
+
+    # Relabel inputs and outputs
+    cpy = convert(sys, inputs='myin', outputs='myout')
+    assert cpy.input_labels == ['myin']
+    assert cpy.output_labels == ['myout']
diff --git a/control/xferfcn.py b/control/xferfcn.py
@@ -1424,16 +1424,13 @@ def _convert_to_transfer_function(sys, inputs=1, outputs=1):
                 num = squeeze(num)  # Convert to 1D array
                 den = squeeze(den)  # Probably not needed
 
-        return TransferFunction(
-            num, den, sys.dt, inputs=sys.input_labels,
-            outputs=sys.output_labels)
+        return TransferFunction(num, den, sys.dt)
 
     elif isinstance(sys, (int, float, complex, np.number)):
         num = [[[sys] for j in range(inputs)] for i in range(outputs)]
         den = [[[1] for j in range(inputs)] for i in range(outputs)]
 
-        return TransferFunction(
-            num, den, inputs=inputs, outputs=outputs)
+        return TransferFunction(num, den)
 
     elif isinstance(sys, FrequencyResponseData):
         raise TypeError("Can't convert given FRD to TransferFunction system.")
@@ -1623,7 +1620,6 @@ def zpk(zeros, poles, gain, *args, **kwargs):
     return TransferFunction(num, den, *args, **kwargs)
 
 
-# TODO: copy signal names
 def ss2tf(*args, **kwargs):
 
     """ss2tf(sys)
@@ -1705,6 +1701,11 @@ def ss2tf(*args, **kwargs):
     if len(args) == 1:
         sys = args[0]
         if isinstance(sys, StateSpace):
+            kwargs = kwargs.copy()
+            if not kwargs.get('inputs'):
+                kwargs['inputs'] = sys.input_labels
+            if not kwargs.get('outputs'):
+                kwargs['outputs'] = sys.output_labels
             return TransferFunction(
                 _convert_to_transfer_function(sys), **kwargs)
         else:
