get_computed_values() method to access computed axis ranges (#5552)

CHANGELOG.md

@@ -4,6 +4,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Added
+- Add `get_computed_values()` method to `BaseFigure` for programmatically accessing values calculated by Plotly.js (starting with computed axis ranges) [[#5552](https://github.com/plotly/plotly.py/issues/5552)]
+
 
 ## [6.7.0] - 2026-04-09
 

plotly/basedatatypes.py

@@ -1447,10 +1447,12 @@ def _select_layout_subplots_by_prefix(
 
         layout_keys_filters = [
             lambda k: k.startswith(prefix) and self.layout[k] is not None,
-            lambda k: row is None
-            or container_to_row_col.get(k, (None, None, None))[0] == row,
-            lambda k: col is None
-            or container_to_row_col.get(k, (None, None, None))[1] == col,
+            lambda k: (
+                row is None or container_to_row_col.get(k, (None, None, None))[0] == row
+            ),
+            lambda k: (
+                col is None or container_to_row_col.get(k, (None, None, None))[1] == col
+            ),
             lambda k: (
                 secondary_y is None
                 or container_to_row_col.get(k, (None, None, None))[2] == secondary_y
@@ -3481,6 +3483,83 @@ def full_figure_for_development(self, warn=True, as_dict=False):
 
         return pio.full_figure_for_development(self, warn, as_dict)
 
+    def get_computed_values(self, include=None):
+        """
+        Retrieve values calculated or derived by Plotly.js during plotting.
+
+        This method provides a lightweight interface to access information that is
+        not explicitly defined in the source figure but is computed by the
+        rendering engine (e.g., autoranged axis limits).
+
+        Note: This initial implementation relies on full_figure_for_development()
+        (via Kaleido) to extract computed values. While the returned object is
+        standard and lightweight, the underlying process triggers a full background
+        render.
+
+        Parameters
+        ----------
+        include: list or tuple of str
+            The calculated values to retrieve. Supported keys include:
+              - 'axis_ranges': The final [min, max] range for each axis.
+            If None, defaults to ['axis_ranges'].
+
+        Returns
+        -------
+        dict
+            A dictionary containing the requested computed values.
+
+        Examples
+        --------
+        >>> import plotly.graph_objects as go
+        >>> fig = go.Figure(go.Scatter(x=[1, 2, 3], y=[10, 20, 30]))
+        >>> fig.get_computed_values(include=['axis_ranges'])
+        {'axis_ranges': {'xaxis': [0.8, 3.2], 'yaxis': [8.0, 32.0]}}
+        """
+        # Validate input
+        # --------------
+        if include is None:
+            include = ["axis_ranges"]
+
+        if not isinstance(include, (list, tuple)):
+            raise ValueError(
+                "The 'include' parameter must be a list or tuple of strings."
+            )
+
+        # Early exit for empty include
+        if not include:
+            return {}
+
+        supported_keys = ["axis_ranges"]
+        for key in include:
+            if key not in supported_keys:
+                raise ValueError(
+                    f"Unsupported key '{key}' in 'include' parameter. "
+                    f"Supported keys are: {supported_keys}"
+                )
+
+        # Retrieve full figure state
+        # --------------------------
+        # We use as_dict=True for efficient traversal of the layout
+        full_fig_dict = self.full_figure_for_development(warn=False, as_dict=True)
+        full_layout = full_fig_dict.get("layout", {})
+
+        result = {}
+
+        # Extract axis ranges
+        # -------------------
+        if "axis_ranges" in include:
+            axis_ranges = {}
+            for key, val in full_layout.items():
+                if key.startswith(("xaxis", "yaxis")):
+                    # Safety checks for axis object and range property
+                    if isinstance(val, dict) and "range" in val:
+                        # Explicit conversion to list for JSON serialization consistency
+                        axis_ranges[key] = list(val["range"])
+
+            result["axis_ranges"] = axis_ranges
+
+        return result
+
     def write_json(self, *args, **kwargs):
         """
         Convert a figure to JSON and write it to a file or writeable

tests/test_core/test_update_objects/test_get_computed_values.py

@@ -0,0 +1,107 @@
+from unittest.mock import MagicMock
+import importlib.metadata
+
+# Mock importlib.metadata.version BEFORE importing plotly to avoid PackageNotFoundError
+if not hasattr(importlib.metadata.version, "assert_called"):
+    importlib.metadata.version = MagicMock(return_value="6.7.0")
+
+from unittest import TestCase
+import plotly.graph_objects as go
+
+
+class TestGetComputedValues(TestCase):
+    def test_get_computed_axis_ranges_basic(self):
+        # Create a simple figure
+        fig = go.Figure(go.Scatter(x=[1, 2, 3], y=[10, 20, 30]))
+
+        # Mock full_figure_for_development to return a dict with computed ranges
+        mock_full_fig = {
+            "layout": {
+                "xaxis": {"range": [0.8, 3.2], "type": "linear"},
+                "yaxis": {"range": [8.0, 32.0], "type": "linear"},
+                "template": {},
+            }
+        }
+        fig.full_figure_for_development = MagicMock(return_value=mock_full_fig)
+
+        # Call get_computed_values
+        computed = fig.get_computed_values(include=["axis_ranges"])
+
+        # Verify results
+        expected = {"axis_ranges": {"xaxis": [0.8, 3.2], "yaxis": [8.0, 32.0]}}
+        self.assertEqual(computed, expected)
+        fig.full_figure_for_development.assert_called_once_with(
+            warn=False, as_dict=True
+        )
+
+    def test_get_computed_axis_ranges_multi_axis(self):
+        # Create a figure with multiple axes
+        fig = go.Figure()
+
+        # Mock full_figure_for_development (returning tuples to test conversion)
+        mock_full_fig = {
+            "layout": {
+                "xaxis": {"range": (0, 1)},
+                "yaxis": {"range": (0, 10)},
+                "xaxis2": {"range": (0, 100)},
+                "yaxis2": {"range": (50, 60)},
+            }
+        }
+        fig.full_figure_for_development = MagicMock(return_value=mock_full_fig)
+
+        computed = fig.get_computed_values(include=["axis_ranges"])
+
+        # Ranges should be converted to lists
+        expected = {
+            "axis_ranges": {
+                "xaxis": [0, 1],
+                "yaxis": [0, 10],
+                "xaxis2": [0, 100],
+                "yaxis2": [50, 60],
+            }
+        }
+        self.assertEqual(computed, expected)
+        # Verify result values are indeed lists
+        for val in computed["axis_ranges"].values():
+            self.assertIsInstance(val, list)
+
+    def test_empty_include(self):
+        fig = go.Figure()
+        fig.full_figure_for_development = MagicMock()
+
+        # Should return empty dict early without calling full_figure
+        computed = fig.get_computed_values(include=[])
+
+        self.assertEqual(computed, {})
+        fig.full_figure_for_development.assert_not_called()
+
+    def test_invalid_include_parameter(self):
+        fig = go.Figure()
+
+        # Test non-list/tuple input
+        with self.assertRaisesRegex(ValueError, "must be a list or tuple of strings"):
+            fig.get_computed_values(include="axis_ranges")
+
+        # Test unsupported key and deterministic error message
+        with self.assertRaisesRegex(
+            ValueError,
+            r"Unsupported key 'invalid'.*Supported keys are: \['axis_ranges'\]",
+        ):
+            fig.get_computed_values(include=["invalid"])
+
+    def test_safe_extraction_handling(self):
+        # Test that non-dict or missing 'range' values are skipped
+        fig = go.Figure()
+        mock_full_fig = {
+            "layout": {
+                "xaxis": "not-a-dict",
+                "yaxis": {"no-range": True},
+                "xaxis2": {"range": [1, 2]},
+            }
+        }
+        fig.full_figure_for_development = MagicMock(return_value=mock_full_fig)
+
+        computed = fig.get_computed_values(include=["axis_ranges"])
+
+        expected = {"axis_ranges": {"xaxis2": [1, 2]}}
+        self.assertEqual(computed, expected)