Affected Repositories

• PyAutoArray (primary)
• PyAutoGalaxy

PyAutoLens needs no change: autolens/plot/__init__.py:12 re-exports plot_array from autogalaxy.util.plot_utils, so the PyAutoGalaxy leg is what satisfies the prompt's aplt.plot_array acceptance criterion for lens users.

Branch Survey

Suggested branch: feature/arcsec-after-decimal

Work Classification

Library (library-first merge gate: PyAutoArray merges before PyAutoGalaxy)

Implementation Steps

1. autoarray/plot/utils.py — _arcsec_labels(ticks, symbol_over_decimal=None). Replace the bare _conf_ticks_flag("symbol_over_decimal", False) read with the argument when it is not None, else the config read. None must keep reading config so every existing caller and the config-driven tests are untouched.
2. autoarray/plot/utils.py — apply_extent(ax, extent, symbol_over_decimal=None), forwarding to both _arcsec_labels calls (lines 1169-1170).
3. autoarray/plot/array.py — add arcsec_after_decimal: Optional[bool] = None to plot_array (cosmetics block) and pass it at the apply_extent call (line 323).
4. autoarray/plot/grid.py (line 181) and autoarray/plot/inversion.py (line 166) — same optional parameter on their public functions, forwarded to apply_extent.
5. autogalaxy/util/plot_utils.py — add arcsec_after_decimal=None to plot_array (line 183) and forward it to autoarray.plot.plot_array.
6. Tests in test_autoarray/plot/test_utils.py — per-call override cases that do not mutate conf.instance, plus one asserting None still honours config.

Key trade-off

The public name differs from the internal one: arcsec_after_decimal on the plotting API (the prompt's name, and the one users read) versus symbol_over_decimal for the config key and internal helpers (already shipped, already documented in general.yaml). Renaming the shipped config key would break anyone who has already set it, so the two names are bridged at the plot_array boundary rather than unified.

Key Files

• autoarray/plot/utils.py — _arcsec_labels (1109), apply_extent (1147)
• autoarray/plot/array.py — plot_array (31), apply_extent call (323)
• autoarray/plot/grid.py (181), autoarray/plot/inversion.py (166)
• autogalaxy/util/plot_utils.py — plot_array (183)
• test_autoarray/plot/test_utils.py — existing arcsec tests (19-90)

Claude Development Prompt: Arcsecond Tick Label Decimal Placement

Type: feature
Target: PyAutoArray
Themes:

• visualization
  Difficulty: large
  Autonomy: supervised
  Priority: normal
  Status: formalised
  Consequence: judge
  Review-minutes: 25
  Unattended: ready
  Filed: 2026-05-14 (backfilled from git)

You are working in the PyAutoLens / PyAutoArray plotting codebase.

Goal

Add a boolean option to the plotting API that changes arcsecond tick labels from the current format:

0.45"
-2.2"
3.1"

to:

0."45
-2."2
3."1

This should be implemented inside the plotting source code, not by user scripts editing Matplotlib tick labels after a figure has been drawn.

Requirements

• Add a clearly named boolean option, for example arcsec_after_decimal, defaulting to False so existing plots are unchanged.
• The option should be available from high-level plotting functions such as autolens.plot.plot_array(...).
• When enabled, only labels that are already formatted as arcseconds should change.
• Preserve all existing tick locations, precision choices, rotation, font size, and other style settings.
• Do not change colorbars or non-arcsecond axis labels.
• Add focused tests or examples covering:
  • default behavior remains 0.45";
  • enabled behavior becomes 0."45;
  • negative values become -2."2;
  • integer-like labels without a decimal either remain unchanged or use a documented behavior.

Suggested Implementation Direction

Find where axis tick labels are formatted in the AutoArray / PyAutoLens plotting stack. Start from:

• autolens.plot.plot_array(...)
• autoarray.plot.plot_array(...)
• the axis / tick helper functions used by autoarray.plot.utils
• any config-driven tick-label formatter that appends the arcsecond symbol

Implement this as close as possible to the tick-label formatter that appends ", rather than modifying labels after plotting. Ideally the formatter should receive the boolean and place the arcsecond marker either at the end or immediately after the decimal point.

Acceptance Criteria

This example should work without post-processing:

import autolens.plot as aplt

aplt.plot_array(
    array=array,
    title="VIS Data",
    arcsec_after_decimal=True,
)

and should produce axis labels like:

-2."2   0."45   3."1

The same call without arcsec_after_decimal=True should preserve the current default labels.

Notes

This request comes from paper-figure generation, where editing Matplotlib labels after aplt.plot_array works but creates fragile layout and whitespace side effects. The source-level option should keep normal PyAutoLens layout behavior intact.