STYLE: Replace UI with IT as index type for LevelSetNode VectorContainer by N-Dekker · Pull Request #6803 · InsightSoftwareConsortium/ITK

N-Dekker · 2026-08-25T18:00:40Z

itk.IT ("IdentifierType") is the most commonly supported index type for VectorContainer. (VectorContainer is wrapped for IT and UC, but not for UI, as index type.)

Follow-up to pull request STYLE: Replace UL with IT as index type in itkPyVectorContainerTest.py #6800

N-Dekker · 2026-08-25T18:35:22Z

Still under construction. I see now: in C++, NodeContainerType also has unsigned int as index type. Probably related.

ITK/Modules/Segmentation/LevelSets/include/itkShapePriorMAPCostFunctionBase.h

Line 84 in 1a6558f

using NodeContainerType = VectorContainer<unsigned int, NodeType>;

dzenanz

Looks good on a glance.

N-Dekker · 2026-08-26T13:49:53Z

This force-pushed amend aims to address CI failures at https://open.cdash.org/tests/2723817696 saying:

  File "/Users/runner/work/1/s-build/Wrapping/Generators/Python/itk/support/template_class.py", line 527, in __getitem__
    this_item = self.__template__[key]
                ~~~~~~~~~~~~~~~~~^^^^^
KeyError: (<itkCType unsigned long>, <class 'itk.itkLevelSetNodePython.itkLevelSetNodeF2'>)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/runner/work/1/s/Modules/Filtering/FastMarching/wrapping/test/FastMarchingImageFilterTest.py", line 131, in <module>
    NodeContainer = itk.VectorContainer[itk.IT, NodeType]
                    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/Users/runner/work/1/s-build/Wrapping/Generators/Python/itk/support/template_class.py", line 531, in __getitem__
    raise itk.TemplateTypeError(self, key)
itk.support.extras.TemplateTypeError: itk.VectorContainer is not wrapped for input type `itk.UL, itk.LevelSetNode[itk.F,2]`.

N-Dekker · 2026-08-26T14:54:58Z


  /** Type of container used to store the level set nodes. */
-  using NodeContainerType = VectorContainer<unsigned int, NodeType>;
+  using NodeContainerType = VectorContainer<NodeType>;


This is a potentially breaking change, although in practice, VectorContainer<unsigned int, NodeType> and VectorContainer<NodeType> behave exactly the same.

`itk.IT` ("IdentifierType") is the most commonly supported index type for VectorContainer. Adjusted Node Container types in C++ to use the default index type of `itk::VectorContainer` (which is equal to `IdentifierType`), instead of `unsigned int`. Adjusted ITKFastMarchingBase.wrap accordingly. Follow-up to pull request InsightSoftwareConsortium#6800 commit 0939d4c "STYLE: Replace UL with IT as index type in itkPyVectorContainerTest.py"

greptile-apps · 2026-08-28T16:28:31Z

Greptile Summary

This change aligns LevelSetNode VectorContainer indices across the FastMarching and ShapePrior native APIs, Python wrapper declarations, and affected Python tests. The C++ aliases now use ITK’s default IdentifierType index, while the wrapper and tests use the corresponding itk.IT specialization.

No defect was identified in the reviewed changes. The focused declarations and Python wrapper registration consistently use the same container index type.

T-Rex validation blocked

Runtime verification of Python container acceptance could not run because the wrapped itk Python package is missing, and the repository’s documented build route requires the missing pixi package manager. The native syntax fallback also cannot run because the generated itkConfigure.h header is unavailable without a configured build tree.

Confidence Score: 5/5

The changed native aliases, wrapper specialization, and Python test call sites consistently use IdentifierType and itk.IT for LevelSetNode containers.

No review findings were emitted. Source inspection found the FastMarching and ShapePrior API container types aligned with the registered Python wrapper specialization and updated test usage.

Files Needing Attention: A configured ITK Python-wrapping build should run the focused FastMarching and ShapePrior Python tests for final runtime coverage; the relevant files are Modules/Filtering/FastMarching/wrapping/ITKFastMarchingBase.wrap and the affected Python test files.

T-Rex Logs

What T-Rex did

Attempted the Python IT LevelSetNode integration probe and encountered a ModuleNotFoundError for itk, preventing container construction.
Tried the wrapped-build configuration via Pixi, but Pixi was not found and the command exited with code 127.
Ran a focused C++ syntax check for the LevelSet alias; it failed because itkConfigure.h was not generated due to a missing configured ITK build tree.
Validated Python probe syntax and bytecode, but the missing wrapper runtime and build tooling prevented observing container acceptance behavior.
Cross-proof validation confirms the same failure modes across proofs: missing itk module, missing Pixi wrapper/build tools, and missing ITK configuration, with no container acceptance observations at this checkout.

_{Ran code and verified through T-Rex}

_{Reviews (1): Last reviewed commit: "STYLE: Replace UI with IT as index type ..." | Re-trigger Greptile}

thewtex

OK, but not terribly excited about this change -- I think unsigned int was probably intended, and there is a breaking type change.

N-Dekker · 2026-08-29T15:48:18Z

OK, but not terribly excited about this change -- I think unsigned int was probably intended, and there is a breaking type change.

Thanks for your comment, @thewtex Looking at the code, I don't see why it was using unsigned int as index type, rather than itk.IT. The underlying std::vector<NodeType> is the same for both VectorContainer specializations, so technically I don't think it matters.

For end-users I think it would be clearer if we just stick with one index type, for VectorContainer. Eventually I think it would also allow us to remove some VectorContainer wrappings, for index types UC and US, but that's beyond the scope of this PR.

hjmjohnson · 2026-09-02T13:48:15Z

I swept this PR through the ITK forest testbed (293 checked-out consumer trees). One downstream break, in ITKSphinxExamples; nothing in the C++ forest is affected. Fix opened as InsightSoftwareConsortium/ITKSphinxExamples#476.

src/Segmentation/LevelSets/SegmentWithGeodesicActiveContourLevelSet/Code.py:106 spells the container explicitly:

seeds = itk.VectorContainer[itk.UI, itk.LevelSetNode[InputPixelType, Dimension]].New()

That instantiation is no longer wrapped after this PR, so the example raises TemplateTypeError at runtime. Since that repo floats across ITK releases and feeds the 5.4 pages on docs.itk.org, #476 guards it rather than switching sides, because the two spellings are disjoint — itk.IT does not resolve on 5.4.7 and itk.UI will not resolve on 6.0.

C++ forest: clear — every consumer reaches the container through the filter's own typedef

Consumer	Site	Why it is fine
ANTs	`Temporary/antsFastMarchingImageFilter.h`, `antsAtroposSegmentationImageFilter.hxx:2588,2804`, `ImageMath_Templates.hxx:8434`	`FastMarchingFilterType::NodeContainer`
BRAINSTools	`GTRACT/Common/itkDtiFastMarchingCostFilter.h`, `gtractCostFastMarching.cxx:185`	`FloatFMType::NodeContainer`
SimpleITK	`FastMarching{,Base,UpwindGradient}ImageFilter.yaml`, `CollidingFrontsImageFilter.yaml`	`typename FilterType::NodeContainer`
ITK-SNAP	`itkParallelSparseFieldLevelSetImageFilterBugFix.h`	unrelated local `ParallelSparseFieldLevelSetNode`

No LevelSetNode usage at all in the other ~280 trees, including every Slicer extension. Other downstream VectorContainer<unsigned int, T> uses (elastix, MITK, Slicer, PlusLib, SlicerExt-PETTumorSegmentation) are unrelated element types and still compile against the two-argument alias.

Since the blast radius is source-level and confined to code that re-spells the template arguments, the ABI-only consumers just recompile.

Why the forest did not catch this on its own

Two independent gaps, both worth noting beyond this PR:

ITKSphinxExamples is in DEFERRED_TARGETS in bin/run-matrix.sh (reason recorded as an ExternalData fetch failure), so the forest's only Python-API consumer is never scored.
The matrix scores PASS/FAIL by artifact existence, so even un-deferred, a runtime TemplateTypeError inside a ctest would still have scored PASS. Catching this class needs the ctest phase, not the build phase.

I am fixing (1) separately; the forest is currently a strong detector of C++/link breakage and a weak one of Python-wrapping breakage, and this PR is purely the latter.

One minor thing on the PR itself: loop counters feeding InsertElement(i, node) are unsigned int in ANTs and SimpleITK and now widen implicitly to SizeValueType. Harmless, and I found no signed counter in the forest that would newly warn under -Wsign-conversion.

N-Dekker changed the title ~~STYLE: Replace UI with IT as index type for LevelSetNode VectorContainer~~ WIP: Replace UI with IT as index type for LevelSetNode VectorContainer Aug 25, 2026

dzenanz approved these changes Aug 25, 2026

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N-Dekker force-pushed the Replace-UI-with-IT-index-type-LevelSetNode-VectorContainer branch from 5bb4e81 to 67912ce Compare August 26, 2026 13:47

github-actions Bot removed the type:Style Style changes: no logic impact (indentation, comments, naming) label Aug 26, 2026

dzenanz approved these changes Aug 26, 2026

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N-Dekker commented Aug 26, 2026

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N-Dekker force-pushed the Replace-UI-with-IT-index-type-LevelSetNode-VectorContainer branch 2 times, most recently from 089ed05 to 4c1b3c9 Compare August 28, 2026 10:01

N-Dekker force-pushed the Replace-UI-with-IT-index-type-LevelSetNode-VectorContainer branch from 4c1b3c9 to 57480cd Compare August 28, 2026 13:22

N-Dekker changed the title ~~WIP: Replace UI with IT as index type for LevelSetNode VectorContainer~~ STYLE: Replace UI with IT as index type for LevelSetNode VectorContainer Aug 28, 2026

N-Dekker marked this pull request as ready for review August 28, 2026 16:20

thewtex reviewed Aug 28, 2026

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hjmjohnson mentioned this pull request Sep 2, 2026

COMP: Keep GeodesicActiveContour example working on ITK 5.4 and 6.0 InsightSoftwareConsortium/ITKSphinxExamples#476

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STYLE: Replace UI with IT as index type for LevelSetNode VectorContainer - #6803

STYLE: Replace UI with IT as index type for LevelSetNode VectorContainer#6803
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