TabularData: Add to_parallel_coordinates.

Uses `ParallelCoordinatesRenderer` and `dvc.render.html.write`.

pre-requisite #4455

dvc/compare.py

@@ -153,6 +153,16 @@ def to_csv(self) -> str:
             writer.writerow(row)
         return buff.getvalue()
 
+    def to_parallel_coordinates(self, output_path, color_by):
+        from dvc.render.html import write
+        from dvc.render.plotly import ParallelCoordinatesRenderer
+
+        index_path = write(
+            output_path,
+            renderers=[ParallelCoordinatesRenderer(self, color_by)],
+        )
+        return index_path.as_uri()
+
     def add_column(self, name: str) -> None:
         self._columns[name] = Column([self._fill_value] * len(self))
         self._keys.append(name)
@@ -173,6 +183,14 @@ def render(self, **kwargs: Any):
 
         if kwargs.pop("csv", False):
             ui.write(self.to_csv(), end="")
+
+        elif kwargs.pop("html", False):
+            ui.write(
+                self.to_parallel_coordinates(
+                    kwargs["output_path"], kwargs.get("color_by")
+                )
+            )
+
         else:
             ui.table(self, headers=self.keys(), **kwargs)
 

tests/unit/test_tabular_data.py

@@ -264,3 +264,21 @@ def test_drop_duplicates_invalid_axis():
 
     with pytest.raises(ValueError, match="Invalid 'axis' value foo."):
         td.drop_duplicates("foo")
+
+
+def test_to_parallel_coordinates(tmp_dir, mocker):
+    (tmp_dir / "foo").mkdir()
+    td = TabularData(["categorical", "scalar"])
+    td.extend([["foo", "0.1"], ["bar", "2"]])
+
+    write = mocker.patch("dvc.render.html.write")
+    renderer_class = mocker.patch(
+        "dvc.render.plotly.ParallelCoordinatesRenderer"
+    )
+    renderer = renderer_class.return_value
+
+    td.render(html=True, output_path="foo")
+
+    renderer_class.assert_called_with(td, None)
+
+    write.assert_called_with("foo", renderers=[renderer])