Infer tendency type by keys

docs/source/yaml_format.rst

@@ -108,6 +108,10 @@ a list of waveforms, or a single number (float or integer).
 
         Refer to the :ref:`Available Tendencies <available-tendencies>` documentation for details on the different tendency types and their parameters.
 
+        .. note::
+            The ``type`` may be omitted. The type of the tendency is then inferred from 
+            the other keys present, if possible.
+
     2.  **Constant Value:** A simple number (integer or float) defines a constant waveform over time.
 
         .. code-block:: yaml

tests/test_waveform.py

@@ -4,6 +4,8 @@
 from waveform_editor.tendencies.constant import ConstantTendency
 from waveform_editor.tendencies.linear import LinearTendency
 from waveform_editor.tendencies.periodic.sine_wave import SineWaveTendency
+from waveform_editor.tendencies.piecewise import PiecewiseLinearTendency
+from waveform_editor.tendencies.repeat import RepeatTendency
 from waveform_editor.tendencies.smooth import SmoothTendency
 from waveform_editor.waveform import Waveform
 
@@ -16,6 +18,34 @@ def test_empty():
     assert waveform.annotations == []
 
 
+@pytest.mark.parametrize(
+    "entry,expected_type",
+    [
+        ({"user_value": 3, "user_duration": 2}, ConstantTendency),
+        (
+            {"user_time": [0, 1, 2], "user_value": [0, 1, 0]},
+            PiecewiseLinearTendency,
+        ),
+        (
+            {
+                "user_waveform": [
+                    {"user_type": "constant", "user_value": 1, "user_duration": 1}
+                ],
+                "user_duration": 2,
+            },
+            RepeatTendency,
+        ),
+        ({"user_to": 5, "user_duration": 2}, LinearTendency),
+        ({"user_duration": 2}, LinearTendency),
+    ],
+    ids=["value", "time+value", "waveform", "to-only", "no-keys"],
+)
+def test_infer_tendency_type(entry, expected_type):
+    waveform = Waveform(waveform=[entry], name="w")
+    assert not waveform.annotations
+    assert type(waveform.tendencies[0]) is expected_type
+
+
 @pytest.fixture
 def waveform_list():
     return [

waveform_editor/waveform.py

@@ -29,7 +29,7 @@
 }
 
 
-tendency_map = {
+TENDENCY_MAP = {
     "linear": LinearTendency,
     "sine-wave": SineWaveTendency,
     "sine": SineWaveTendency,
@@ -45,6 +45,28 @@
     "repeat": RepeatTendency,
 }
 
+INFERRED_TYPE_BY_KEY = {
+    "user_time": PiecewiseLinearTendency,
+    "user_value": ConstantTendency,
+    "user_waveform": RepeatTendency,
+}
+
+
+def _infer_tendency_class(entry):
+    """Infer a tendency's class from keys in the tendency entry, defaulting to
+    linear tendency if no distinctive keys are present.
+
+    Args:
+        entry: Entry in the YAML file.
+
+    Returns:
+        The inferred tendency class.
+    """
+    for key, tendency_class in INFERRED_TYPE_BY_KEY.items():
+        if key in entry:
+            return tendency_class
+    return LinearTendency
+
 
 class Waveform(BaseWaveform):
     def __init__(
@@ -240,44 +262,6 @@ def update_annotations(self, event=None):
             if tendency.annotations and tendency.annotations not in self.annotations:
                 self.annotations.add_annotations(tendency.annotations)
 
-    def _has_type_error(self, entry):
-        """Check if the YAML entry contains an error related to the tendency type.
-
-        Args:
-            entry: Entry in the YAML file.
-
-        Returns:
-            True if there is a type error, False otherwise.
-        """
-        line_number = entry.get("line_number", 0)
-        ignore_msg = "This tendency will be ignored.\n"
-
-        # If no type is given, take linear as default
-        if "user_type" not in entry:
-            entry["user_type"] = "linear"
-
-        tendency_type = entry.get("user_type", None)
-        if tendency_type is None:
-            error_msg = f"The tendency type cannot be empty.\n{ignore_msg}"
-            self.annotations.add(line_number, error_msg)
-            return True
-
-        if not isinstance(tendency_type, str):
-            error_msg = f"The tendency type should be of type 'string'.\n{ignore_msg}"
-            self.annotations.add(line_number, error_msg)
-            return True
-
-        if tendency_type not in tendency_map:
-            suggestion = self.annotations.suggest(tendency_type, tendency_map.keys())
-
-            error_msg = (
-                f"Unsupported tendency type: '{tendency_type}'. {suggestion}"
-                f"{ignore_msg}"
-            )
-            self.annotations.add(line_number, error_msg)
-            return True
-        return False
-
     def get_yaml_string(self):
         """Converts the internal YAML waveform description to a string.
 
@@ -305,10 +289,20 @@ def _handle_tendency(self, entry):
         Returns:
             The created tendency or None, if the tendency cannot be created
         """
-        if self._has_type_error(entry):
-            return None
+        # If no type is given, infer it from the entry's keys
+        if "user_type" not in entry:
+            tendency_class = _infer_tendency_class(entry)
         else:
-            tendency_type = entry.pop("user_type")
-            tendency_class = tendency_map[tendency_type]
-            tendency = tendency_class(**entry)
-            return tendency
+            user_type = entry.pop("user_type")
+            user_type = "" if user_type is None else str(user_type)
+            tendency_class = TENDENCY_MAP.get(user_type)
+            if tendency_class is None:
+                suggestion = self.annotations.suggest(user_type, TENDENCY_MAP.keys())
+                error_msg = (
+                    f"Unsupported tendency type: '{user_type}'. "
+                    f"{suggestion}This tendency will be ignored.\n"
+                )
+                self.annotations.add(entry.get("line_number", 0), error_msg)
+                return None
+
+        return tendency_class(**entry)