Raise error when trying to resolve to display names with duplicates.

src/enlyze/errors.py

@@ -28,3 +28,11 @@ class ResamplingValidationError(EnlyzeError):
  resampling interval is specified.
 
  """
+
+
+class DuplicateDisplayNameError(EnlyzeError):
+ """Variables with duplicate display names
+
+ Resolving variable UUIDs to display names would result in ambiguity because
+ multiple variables have the same display name.
+ """

src/enlyze/models.py

@@ -7,6 +7,7 @@
 
 import pandas
 
+from enlyze.errors import DuplicateDisplayNameError
 from enlyze.schema import dataframe_ensure_schema
 
 
@@ -143,6 +144,19 @@ def _display_names_as_column_names(self, columns: list[str]) -> list[str]:
  if var.display_name
  }
 
+ distinct_display_names = set(uuid_to_display_name.values())
+ if len(uuid_to_display_name) != len(distinct_display_names):
+ maybe_duplicate_display_names = list(uuid_to_display_name.values())
+ for name in distinct_display_names:
+ maybe_duplicate_display_names.remove(name)
+
+ raise DuplicateDisplayNameError(
+ ", ".join(
+ f"'{duplicate_display_name}'"
+ for duplicate_display_name in set(maybe_duplicate_display_names)
+ )
+ )
+
  return [uuid_to_display_name.get(var_uuid, var_uuid) for var_uuid in columns]
 
  def to_dicts(self, use_display_names: bool = False) -> Iterator[dict[str, Any]]:
@@ -153,13 +167,11 @@ def to_dicts(self, use_display_names: bool = False) -> Iterator[dict[str, Any]]:
  <python:datetime-naive-aware>` :py:class:`datetime.datetime` localized in UTC.
 
  :param use_display_names: Whether to return display names instead of variable
- UUIDs. If there is no display name, fall back to UUID. Display names aren't
- guaranteed to be unique, duplicate columns will not be returned.
+ UUIDs. If there is no display name, fall back to UUID.
 
  :returns: Iterator over rows
 
  """
-
  time_column, *variable_columns = self._columns
 
  if use_display_names:
@@ -182,9 +194,7 @@ def to_dataframe(self, use_display_names: bool = False) -> pandas.DataFrame:
  represented as a column named by its UUID.
 
  :param use_display_names: Whether to return display names instead of variable
- UUIDs. If there is no display name, fall back to UUID. Display names aren't
- guaranteed to be unique, so the DataFrame may contain multiple columns with
- the same name.
+ UUIDs. If there is no display name, fall back to UUID.
 
  :returns: DataFrame with timeseries data indexed by time
 

tests/enlyze/test_models.py

@@ -1,9 +1,13 @@
 from dataclasses import replace
+from datetime import datetime
+from uuid import uuid4
 
 import hypothesis.strategies as st
+import pytest
 from hypothesis import given
 
-from enlyze.models import ProductionRun, ProductionRuns
+from enlyze.errors import DuplicateDisplayNameError
+from enlyze.models import ProductionRun, ProductionRuns, TimeseriesData, Variable
 
 
 @given(runs=st.lists(st.from_type(ProductionRun), max_size=10))
@@ -28,3 +32,21 @@ def test_production_runs_to_dataframe_no_empty_columns_for_optional_dataclasses(
 
  assert "quantity_total" not in df.columns
  assert "average_throughput" in df.columns
+
+
+@given(variable=st.builds(Variable, display_name=st.text(min_size=1)))
+def test_timeseries_data_duplicate_display_names(variable):
+
+ variable_duplicate = replace(variable, uuid=uuid4())
+ variables = [variable, variable_duplicate]
+
+ data = TimeseriesData(
+ start=datetime.now(),
+ end=datetime.now(),
+ variables=variables,
+ _columns=["time", *[str(v.uuid) for v in variables]],
+ _records=[],
+ )
+
+ with pytest.raises(DuplicateDisplayNameError):
+ data.to_dataframe(use_display_names=True)