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Support numpy >= 2.4 and relax the numpy requirement to <3 - #101

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ICAMS:masterfrom
pmrv:numpy-compat-upstream
Sep 4, 2026
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Support numpy >= 2.4 and relax the numpy requirement to <3#101
srmnitc merged 2 commits into
ICAMS:masterfrom
pmrv:numpy-compat-upstream

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@pmrv pmrv commented Jul 16, 2026

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Two changes are needed to work with numpy 2.4, both backward compatible down to numpy 1.x:

  1. PyACECalculator/PyACEEnsembleCalculator filled the ASE results dict via np.float64(energy.reshape(-1,)). numpy 2.4 expired the 'conversion of ndim > 0 arrays to scalars' deprecation (present since numpy 1.25), so the scalar constructor now returns a shape-(1,) array instead of collapsing it to a scalar, and atoms.get_potential_energy() leaked a 1-element array of the total energy. Scalar results now go through float(), which behaves identically on every numpy version, and per-atom arrays through astype(np.float64), which also keeps energies_dev/forces_dev arrays for single-atom structures on older numpy.

  2. pyace.radial used np.trapz, which numpy 2.0 kept only as a deprecated alias of np.trapezoid and numpy 2.4 removed. The module now picks whichever of the two exists.

A regression assertion in tests/test_PyACECalculator.py guards the scalar energy output. Verified by building the package and running tests/test_PyACECalculator.py against numpy 1.26.4, 2.3.5 and 2.4.6.

Claude-Session: https://claude.ai/code/session_015Ui6Drmop9gZXo1fgn8yVg

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Two changes are needed to work with numpy 2.4, both backward
compatible down to numpy 1.x:

1. PyACECalculator/PyACEEnsembleCalculator filled the ASE results dict
   via np.float64(energy.reshape(-1,)). numpy 2.4 expired the
   'conversion of ndim > 0 arrays to scalars' deprecation (present
   since numpy 1.25), so the scalar constructor now returns a
   shape-(1,) array instead of collapsing it to a scalar, and
   atoms.get_potential_energy() leaked a 1-element array of the total
   energy. Scalar results now go through float(), which behaves
   identically on every numpy version, and per-atom arrays through
   astype(np.float64), which also keeps energies_dev/forces_dev arrays
   for single-atom structures on older numpy.

2. pyace.radial used np.trapz, which numpy 2.0 kept only as a
   deprecated alias of np.trapezoid and numpy 2.4 removed. The module
   now picks whichever of the two exists.

A regression assertion in tests/test_PyACECalculator.py guards the
scalar energy output. Verified by building the package and running
tests/test_PyACECalculator.py against numpy 1.26.4, 2.3.5 and 2.4.6.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015Ui6Drmop9gZXo1fgn8yVg
Bring in the CI fixes that landed after this branch was cut, so the
pipeline can run at all.

Both jobs on this PR failed in "Test with python-ace with tensorpotential"
for reasons unrelated to this branch: collection aborted on a missing
maxvolpy, so no test ran. Master fixed that in 3bfa4df (install
lib/maxvolpy explicitly, since `pip install .` builds a wheel and never
runs setup.py's InstallMaxVolPyLocalPackage hook) and d63466f
(UnitCellFilter moved to ase.filters).

Merge is clean. Both sides touch tests/test_PyACECalculator.py in
different tests - the scalar-energy assertion in test_setup here,
UnitCellFilter in test_relaxation from master - and both survived.

Independently verified this branch's premises against numpy 1.26.4,
2.3.5, 2.4.6 and 2.5.2:

  * np.float64(energy.reshape(-1,)) returns a float64 scalar (with a
    DeprecationWarning) up to 2.3.5 but a shape-(1,) ndarray from 2.4.6
    on, so get_potential_energy() did leak an array, as described.
  * ACECalculator::energy is `DOUBLE_TYPE energy`, a plain double, so
    np.array() of it is 0-d and float() on it is exact and unwarned on
    all four versions.
  * Dropping the .reshape(-1,) is load-bearing, not cosmetic:
    float() on a shape-(1,) array still warns up to 2.3.5 and raises
    TypeError("only 0-dimensional arrays can be converted to Python
    scalars") from 2.4.6 on. Keeping the reshape would have crashed.
  * np.trapz is present up to 2.3.5 and gone from 2.4.6; np.trapezoid
    covers 2.x. The shim picks correctly on each.
  * np.float64(energies_dev) collapsed a 1-atom array to a scalar on
    older numpy, so .astype(np.float64) is the more consistent fix, as
    the PR argues. For the 4-atom structure in test_calculator.py both
    spellings give shape (4,), so that assertion is unaffected.

Caveat worth recording: a green run here does NOT exercise numpy 2.x.
TensorPotential pins numpy<=1.26.4 and is installed first, and pip does
not upgrade an already-satisfied requirement, so both jobs still resolve
numpy 1.26.4 whether the pin here reads <=1.26.4 or <3. CI can only show
this change does not regress numpy 1.26.4; the 2.4 support it claims
rests on local verification. Testing that in CI needs TensorPotential's
own cap raised first.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
srmnitc added a commit to pmrv/python-ace that referenced this pull request Sep 4, 2026
Bring in master and drop this branch's now-redundant copies of the two CI
fixes, leaving the pandas bound as its only net change.

This branch (15 Jul) found both CI problems before ICAMS#104 did and carried
its own fixes for them, so master and this branch fixed the same two
things independently and both files conflicted:

  * .github/workflows/test.yml - both add an "Install maxvolpy" step.
    Resolved to master's: it installs `Cython scipy` rather than only
    `cython`, and spells out why --no-build-isolation is needed.
  * tests/test_PyACECalculator.py - both wrap the UnitCellFilter import.
    Identical logic, only comment placement differed; resolved to
    master's.

Both files are now byte-identical to master, so the net diff against
master is the single setup.py line this PR is actually about.

Verified the pandas audit rather than assuming it:

  * No use of APIs dropped in pandas 2/3 - no applymap, iteritems,
    delim_whitespace, .ix, get_values or lookup anywhere. Every
    `.append(` hit is a plain list; preparedata.py:706 appends to a list
    and then calls pd.concat, which is the modern pattern.
  * The `>=2` floor holds. paralleldataexecutor.py:68 looked like a
    DataFrame.map (pandas 2.1+) risk given the `batch_df` name, but the
    call is guarded by `isinstance(batch_df, pd.Series)` and DataFrames
    take the `.apply(..., axis=1)` branch, so nothing needs 2.1.
  * No chained assignment on DataFrames; writes go through df[col] = or
    df.loc[mask, col] =. The inplace=True calls that do exist (drop,
    dropna, reset_index) are on owned frames, not slices.
  * All 12 pickled frames in the repo load under pandas 3.0.5 / numpy
    2.5.2, not just the exmpl_df cited in the PR. Nine of them are
    pyace.preparedata.DataFrameWithMetadata, a pd.DataFrame subclass
    with _metadata and a _constructor override - the part most exposed
    to pandas 3 - and they rebuild with the metadata attribute intact
    and object dtypes preserved. index.map(str), Series.map(len),
    df[col] =, df.loc[mask, col] = and pd.concat all run clean on the
    loaded frames with no CoW warnings.

Caveat: a green run here does not exercise pandas 3, for two independent
reasons. pandas 3.0 requires Python >= 3.11 and this matrix is 3.9/3.10,
so it cannot be installed at all; and TensorPotential pins pandas<=2.0
and is installed first, so both jobs resolve pandas 2.0.0 whichever bound
this file carries. CI can only show no regression against pandas 2.0.0.
Same shape of gap as ICAMS#101 has for numpy.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
@srmnitc
srmnitc merged commit 490ce8c into ICAMS:master Sep 4, 2026
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3 participants