add ability to use signal base names in interconnect()

murrayrm · murrayrm · commit 40e6021a330e · 2023-06-06T20:58:21.000-07:00
diff --git a/control/iosys.py b/control/iosys.py
@@ -29,7 +29,6 @@
 import numpy as np
 import scipy as sp
 import copy
-import itertools
 from warnings import warn
 
 from .lti import LTI
@@ -1011,7 +1010,7 @@ def __init__(self, syslist, connections=None, inplist=None, outlist=None,
                 output_indices, gain = self._parse_output_spec(output_spec)
                 if len(output_indices) != len(input_indices):
                     raise ValueError(
-                        f"inconsistent number signals in connecting"
+                        f"inconsistent number of signals in connecting"
                         f" '{output_spec}' to '{connection[0]}'")
 
                 for input_index, output_index in zip(
@@ -2541,7 +2540,8 @@ def interconnect(
         signals are given names, then the forms 'sys.sig' or ('sys', 'sig')
         are also recognized.  Finally, for multivariable systems the signal
         index can be given as a list, for example '(subsys_i, [inp_j1, ...,
-        inp_jn])' or as as a slice, for example, 'sys.sig[i:j]'.
+        inp_jn])', as as a slice, for example, 'sys.sig[i:j]', or as a base
+        name `sys.sig` (which matches `sys.sig[i]`).
 
         Similarly, each output-spec should describe an output signal from
         one of the subsystems.  The lowest level representation is a tuple
@@ -2552,9 +2552,9 @@ def interconnect(
         subsystem are used.  If systems and signals are given names, then
         the form 'sys.sig', ('sys', 'sig') or ('sys', 'sig', gain) are also
         recognized, and the special form '-sys.sig' can be used to specify
-        a signal with gain -1.  Lists and slices can also be used, as long
-        as the number of elements for each output spec mataches the input
-        spec.
+        a signal with gain -1.  Lists, slices, and base names can also be
+        used, as long as the number of elements for each output spec
+        mataches the input spec.
 
         If omitted, the `interconnect` function will attempt to create the
         interconnection map by connecting all signals with the same base names
@@ -2685,11 +2685,12 @@ def interconnect(
     ...     outlist=['P.y[0]', 'P.y[1]'],
     ... )
 
-    This expression can be simplified using slice notation:
+    This expression can be simplified using either slice notation or
+    just signal basenames:
 
     >>> T = ct.interconnect(
-    ...     [P, C], connections=[['P.u[:]', 'C.y[:]'], ['C.u[:]', '-P.y[:]']],
-    ...     inplist='C.u[:]', outlist='P.y[:]')
+    ...     [P, C], connections=[['P.u[:]', 'C.y[:]'], ['C.u', '-P.y']],
+    ...     inplist='C.u', outlist='P.y[:]')
 
     or further simplified by omitting the input and output signal
     specifications (since all inputs and outputs are used):
@@ -2775,6 +2776,11 @@ def interconnect(
         # Use an empty connections list
         connections = []
 
+    elif isinstance(connections, list) and \
+         all([isinstance(cnxn, (str, tuple)) for cnxn in connections]):
+        # Special case where there is a single connection
+        connections = [connections]
+
     # If inplist/outlist is not present, try using inputs/outputs instead
     if inplist is None:
         inplist = list(inputs or [])
diff --git a/control/namedio.py b/control/namedio.py
@@ -113,19 +113,26 @@ def _find_signals(self, name_list, sigdict):
 
         index_list = []
         for name in name_list:
-            # Look for signal ranges (slice-like)
-            m = re.match(r'([\w$]+)\[([\d]*):([\d]*)\]$', name)
-            if m:
-                base = m.group(1)
-                start = None if m.group(2) == '' else int(m.group(2))
-                stop = None if m.group(3) == '' else int(m.group(3))
+            # Look for signal ranges (slice-like or base name)
+            ms = re.match(r'([\w$]+)\[([\d]*):([\d]*)\]$', name)  # slice
+            mb = re.match(r'([\w$]+)$', name)                     # base
+            if ms:
+                base = ms.group(1)
+                start = None if ms.group(2) == '' else int(ms.group(2))
+                stop = None if ms.group(3) == '' else int(ms.group(3))
                 for var in sigdict:
                     # Find variables that match
-                    msig = re.match(r'([\w$]+)\[([\d]*)\]$', var)
+                    msig = re.match(r'([\w$]+)\[([\d]+)\]$', var)
                     if msig.group(1) == base and \
                        (start is None or int(msig.group(2)) >= start) and \
                        (stop is None or int(msig.group(2)) < stop):
                             index_list.append(int(msig.group(2)))
+            elif mb and sigdict.get(name, None) is None:
+                # Try to use name as a base name
+                for var in sigdict:
+                    msig = re.match(name + r'\[([\d]+)\]$', var)
+                    if msig:
+                        index_list.append(int(msig.group(1)))
             else:
                 index_list.append(sigdict.get(name, None))
 
diff --git a/control/tests/iosys_test.py b/control/tests/iosys_test.py
@@ -2066,6 +2066,9 @@ def test_iosys_sample():
             [['sys2.u[0:3]', 'sys1.y[:]']],
             'sys1.u[:]', ['sys2.y[0:3]'], None, None,
             id="signal slices"),
+        pytest.param(
+            ['sys2.u', 'sys1.y'], 'sys1.u', 'sys2.y', None, None,
+            id="signal basenames"),
         pytest.param(
             [[('sys2', [0, 1, 2]), ('sys1', [0, 1, 2])]],
             [('sys1', [0, 1, 2])], [('sys2', [0, 1, 2])],
