Fix issue with first-order WDF allpass sections

b_asic/sfg_generators.py

@@ -13,7 +13,6 @@ from b_asic.core_operations import (
     Name,
     SymmetricTwoportAdaptor,
 )
-from b_asic.port import InputPort, OutputPort
 from b_asic.signal import Signal
 from b_asic.signal_flow_graph import SFG
 from b_asic.special_operations import Delay, Input, Output
@@ -51,7 +50,7 @@ def wdf_allpass(
     -------
         Signal flow graph
     """
-    np_coefficients = np.squeeze(np.asarray(coefficients))
+    np_coefficients = np.atleast_1d(np.squeeze(np.asarray(coefficients)))
     order = len(np_coefficients)
     if not order:
         raise ValueError("Coefficients cannot be empty")
@@ -143,7 +142,7 @@ def direct_form_fir(
     --------
     transposed_direct_form_fir
     """
-    np_coefficients = np.squeeze(np.asarray(coefficients))
+    np_coefficients = np.atleast_1d(np.squeeze(np.asarray(coefficients)))
     taps = len(np_coefficients)
     if not taps:
         raise ValueError("Coefficients cannot be empty")
@@ -211,7 +210,7 @@ def transposed_direct_form_fir(
     --------
     direct_form_fir
     """
-    np_coefficients = np.squeeze(np.asarray(coefficients))
+    np_coefficients = np.atleast_1d(np.squeeze(np.asarray(coefficients)))
     taps = len(np_coefficients)
     if not taps:
         raise ValueError("Coefficients cannot be empty")

test/test_sfg_generators.py

 import numpy as np
+import pytest
 
 from b_asic.core_operations import (
     Addition,
@@ -16,6 +17,7 @@ from b_asic.special_operations import Delay
 
 
 def test_wdf_allpass():
+    # Third-order
     sfg = wdf_allpass([0.3, 0.5, 0.7])
     assert (
         len(
@@ -28,6 +30,9 @@ def test_wdf_allpass():
         == 3
     )
 
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 3
+
+    # Fourth-order
     sfg = wdf_allpass([0.3, 0.5, 0.7, 0.9])
     assert (
         len(
@@ -40,6 +45,34 @@ def test_wdf_allpass():
         == 4
     )
 
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 4
+
+    # First-order
+    sfg = wdf_allpass([0.3])
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, SymmetricTwoportAdaptor)
+            ]
+        )
+        == 1
+    )
+
+    # First-order with scalar input (happens to work)
+    sfg = wdf_allpass(0.3)
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, SymmetricTwoportAdaptor)
+            ]
+        )
+        == 1
+    )
+
 
 def test_direct_form_fir():
     impulse_response = [0.3, 0.5, 0.7]
@@ -75,6 +108,36 @@ def test_direct_form_fir():
     impulse_response.append(0.0)
     assert np.allclose(sim.results['0'], impulse_response)
 
+    impulse_response = [0.3]
+    sfg = direct_form_fir(impulse_response)
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, ConstantMultiplication)
+            ]
+        )
+        == 1
+    )
+    assert len([comp for comp in sfg.components if isinstance(comp, Addition)]) == 0
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 0
+
+    impulse_response = 0.3
+    sfg = direct_form_fir(impulse_response)
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, ConstantMultiplication)
+            ]
+        )
+        == 1
+    )
+    assert len([comp for comp in sfg.components if isinstance(comp, Addition)]) == 0
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 0
+
 
 def test_transposed_direct_form_fir():
     impulse_response = [0.3, 0.5, 0.7]
@@ -109,3 +172,42 @@ def test_transposed_direct_form_fir():
     sim.run_for(6)
     impulse_response.append(0.0)
     assert np.allclose(sim.results['0'], impulse_response)
+
+    impulse_response = [0.3]
+    sfg = transposed_direct_form_fir(impulse_response)
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, ConstantMultiplication)
+            ]
+        )
+        == 1
+    )
+    assert len([comp for comp in sfg.components if isinstance(comp, Addition)]) == 0
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 0
+
+    impulse_response = 0.3
+    sfg = transposed_direct_form_fir(impulse_response)
+    assert (
+        len(
+            [
+                comp
+                for comp in sfg.components
+                if isinstance(comp, ConstantMultiplication)
+            ]
+        )
+        == 1
+    )
+    assert len([comp for comp in sfg.components if isinstance(comp, Addition)]) == 0
+    assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 0
+
+
+def test_sfg_generator_errors():
+    sfg_gens = [wdf_allpass, transposed_direct_form_fir, direct_form_fir]
+    for gen in sfg_gens:
+        with pytest.raises(ValueError, match="Coefficients cannot be empty"):
+            gen([])
+        with pytest.raises(TypeError, match="coefficients must be a 1D-array"):
+            gen([[1, 2], [1, 3]])