feat: DH-20808: Add subplot_titles and title parameters to make_subplots #1260

Copilot · 2025-11-07T20:53:22Z

Added subplot_titles argument to make_subplots that can either pass in a list of new subplot titles or be set to True to maintain existing subplot titles.
Added title argument to make_subplots as well, similar to other charts.

…_subplots Co-authored-by: jnumainville <[email protected]>

Co-authored-by: jnumainville <[email protected]>

…ncation logic Co-authored-by: jnumainville <[email protected]>

…title check Co-authored-by: jnumainville <[email protected]>

Co-authored-by: jnumainville <[email protected]>

jnumainville · 2025-11-07T21:28:35Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

        'b' is a float that adds bottom padding
        'rowspan' is an int to make this figure span multiple rows
        'colspan' is an int to make this figure span multiple columns
+      subplot_titles: (Default value = None)


We don't need to provide defaults like this in the docs. Any existing form of this can be considered incorrect.

Removed default value annotations from docstrings in commit eaed59c.

jnumainville · 2025-11-07T21:33:03Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+        is desired in that space. Cannot be used with use_existing_titles.
+      use_existing_titles: (Default value = False)
+        If True, automatically extracts and uses titles from the input figures
+        as subplot titles. Cannot be used with subplot_titles.


I want a more specific name for use_existing_titles that makes what the parameter does clear. How about titles_as_subtitles.

Renamed to titles_as_subtitles for better clarity in commit eaed59c.

jnumainville · 2025-11-07T21:37:19Z

plugins/plotly-express/docs/sub-plots.md

+
+### Adding Subplot Titles
+
+You can add titles to individual subplots using the `subplot_titles` parameter. Provide a list or tuple of titles in row-major order.


"row-major" is a bit too jargony. Use simpler language for this term.

Updated to use simpler language: "ordered from left to right, top to bottom" in commit eaed59c.

jnumainville · 2025-11-07T21:42:21Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+    if use_existing_titles:
+        # Extract titles from existing figures
+        # Since grid is already reversed, we need to extract in reversed order
+        # to get titles in natural top-to-bottom order
+        for fig_row in reversed(grid):
+            for fig in fig_row:
+                if fig is None:
+                    final_subplot_titles.append("")
+                else:
+                    extracted_title = extract_title_from_figure(fig)
+                    # Explicitly check for None to handle empty strings correctly
+                    final_subplot_titles.append(
+                        extracted_title if extracted_title is not None else ""
+                    )
+    elif subplot_titles is not None:
+        # Convert to list if tuple
+        final_subplot_titles = list(subplot_titles)
+
+        # Validate and adjust length if needed
+        total_subplots = rows * cols
+        if len(final_subplot_titles) > total_subplots:
+            # Truncate if too many titles provided
+            final_subplot_titles = final_subplot_titles[:total_subplots]
+        elif len(final_subplot_titles) < total_subplots:
+            # Pad with empty strings if too few titles provided
+            final_subplot_titles.extend(
+                [""] * (total_subplots - len(final_subplot_titles))
+            )


This logic seems overly complex. It could be combined into a generator, and at the very least it should be put into a function so it matches the level of abstraction as the existing function.

Extracted into get_subplot_titles helper function for better abstraction in commit eaed59c.

jnumainville · 2025-11-07T21:44:44Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+    # Create the custom update function to add annotations and title
+    def custom_update_figure(fig: Figure) -> Figure:
+        # Add subplot title annotations if any
+        if final_subplot_titles:
+            annotations = create_subplot_annotations(
+                final_subplot_titles,
+                col_starts,
+                col_ends,
+                row_starts,
+                row_ends,
+                rows,
+                cols,
+            )
+
+            # Get existing annotations if any
+            existing_annotations = (
+                list(fig.layout.annotations) if fig.layout.annotations else []
+            )
+            fig.update_layout(annotations=existing_annotations + annotations)
+
+        # Add overall title if provided
+        if title:
+            fig.update_layout(title=title)
+
+        # Apply user's unsafe_update_figure if provided
+        result = unsafe_update_figure(fig)
+        return result if result is not None else fig


This shouldn't be structured this way. The functionality should be within atomic_layer itself rather than trying to use the unsafe update in this way.

Moved annotation and title logic directly into atomic_layer via new subplot_annotations and overall_title parameters in commit eaed59c.

jnumainville · 2025-11-07T21:47:51Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+
+        # Add overall title if provided
+        if title:
+            fig.update_layout(title=title)


this should also be an argument to layer

Added overall_title parameter to both atomic_layer and layer functions in commit eaed59c.

jnumainville · 2025-11-07T21:50:27Z

@copilot address comments

- Rename use_existing_titles to titles_as_subtitles for clarity - Remove default value annotations from docstrings - Extract title handling logic into get_subplot_titles helper function - Move annotation and title application from unsafe_update_figure to atomic_layer - Add subplot_annotations and overall_title parameters to atomic_layer and layer - Update documentation to use simpler language (left to right, top to bottom instead of row-major) - Update all tests to use titles_as_subtitles - Simplify extract_title_from_figure to always return string Co-authored-by: jnumainville <[email protected]>

jnumainville · 2025-11-07T22:06:54Z

plugins/plotly-express/src/deephaven/plot/express/plots/_layer.py

        Used to add any custom changes to the underlying plotly figure. Note that
        the existing data traces should not be removed. This may lead to unexpected
        behavior if traces are modified in a way that break data mappings.
+      overall_title:


this should just be title

Changed to title in commit 10b6052.

jnumainville · 2025-11-07T22:13:18Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+        elif len(titles) < total_subplots:
+            titles.extend([""] * (total_subplots - len(titles)))


You don't need to pad the list. If there is less than expected, there will just be no annotations there anyways, which get skipped later.

Removed padding logic - annotations are skipped for missing titles in commit 10b6052.

jnumainville · 2025-11-07T22:14:01Z

plugins/plotly-express/src/deephaven/plot/express/plots/subplots.py

+            cols,
+        )
+
+    return atomic_layer([""] * (total_subplots - len(final_subplot_titles)))


this call of atomic_layer seems like it shouldn't be here

Removed erroneous duplicate return statement in commit 10b6052.

jnumainville · 2025-11-07T22:17:40Z

@copilot address comments

- Rename 'overall_title' parameter to 'title' in layer function - Remove unnecessary padding logic from get_subplot_titles (annotations are skipped for missing titles anyway) - Remove erroneous duplicate return statement in atomic_make_subplots Co-authored-by: jnumainville <[email protected]>

…itles-argument

jnumainville · 2026-01-26T22:59:20Z

Closing in favor of #1283

Initial plan

c460b14

Copilot AI assigned Copilot and jnumainville Nov 7, 2025

Copilot started work on behalf of jnumainville November 7, 2025 20:53 View session

Copilot AI and others added 7 commits November 7, 2025 21:05

Add subplot_titles, use_existing_titles, and title parameters to make…

74d3ae4

…_subplots Co-authored-by: jnumainville <[email protected]>

Apply black formatting to subplots code and tests

8adf354

Co-authored-by: jnumainville <[email protected]>

Apply blacken-docs formatting to sub-plots.md documentation

c339107

Co-authored-by: jnumainville <[email protected]>

Fix row calculation for subplot titles to account for reversed grid

6292cc4

Co-authored-by: jnumainville <[email protected]>

Address code review feedback: improve None handling and add title tru…

287266f

…ncation logic Co-authored-by: jnumainville <[email protected]>

Refactor annotation logic: extract helper function and improve empty …

7a5f519

…title check Co-authored-by: jnumainville <[email protected]>

Simplify title check by removing redundant isinstance

5e6d609

Co-authored-by: jnumainville <[email protected]>

Copilot AI changed the title ~~[WIP] Add subplot_titles argument to make_subplots~~ Add subplot_titles, use_existing_titles, and title parameters to make_subplots Nov 7, 2025

Copilot AI requested a review from jnumainville November 7, 2025 21:21

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Copilot started work on behalf of jnumainville November 7, 2025 21:50 View session

Copilot AI changed the title ~~Add subplot_titles, use_existing_titles, and title parameters to make_subplots~~ Add subplot_titles, titles_as_subtitles, and title parameters to make_subplots Nov 7, 2025

Copilot AI requested a review from jnumainville November 7, 2025 22:02

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jnumainville requested changes Nov 7, 2025

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Copilot AI requested a review from jnumainville November 7, 2025 22:24

Copilot finished work on behalf of jnumainville November 7, 2025 22:24

tweaks and testing

a070a6b

jnumainville changed the title ~~Add subplot_titles, titles_as_subtitles, and title parameters to make_subplots~~ feat: DH-20808: Add subplot_titles, titles_as_subtitles, and title parameters to make_subplots Jan 26, 2026

jnumainville changed the title ~~feat: DH-20808: Add subplot_titles, titles_as_subtitles, and title parameters to make_subplots~~ feat: DH-20808: Add subplot_titles and title parameters to make_subplots Jan 26, 2026

jnumainville requested review from a team and jnumainville and removed request for a team and jnumainville January 26, 2026 21:23

jnumainville unassigned Copilot Jan 26, 2026

jnumainville requested review from a team, jnumainville and mofojed and removed request for a team and jnumainville January 26, 2026 21:23

jnumainville added 2 commits January 26, 2026 15:28

Merge remote-tracking branch 'origin/main' into copilot/add-subplot-t…

079fd83

…itles-argument

Merge remote-tracking branch 'origin/main' into copilot/add-subplot-t…

035f43b

…itles-argument

jnumainville closed this Jan 26, 2026


		### Adding Subplot Titles

		You can add titles to individual subplots using the `subplot_titles` parameter. Provide a list or tuple of titles in row-major order.

		elif len(titles) < total_subplots:
		titles.extend([""] * (total_subplots - len(titles)))

feat: DH-20808: Add subplot_titles and title parameters to make_subplots #1260

feat: DH-20808: Add subplot_titles and title parameters to make_subplots #1260

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