---
categories:
- healpy
- python
date: '2026-07-23'
layout: post
title: 'Release of healpy 1.20.0'
---

I am pleased to announce the release of healpy 1.20.0.

This release includes several important updates, including dropping support for NumPy 1.x,
performance optimizations, and the introduction of new harmonic downgrading features.

You can install the new version from [PyPI](https://pypi.org/project/healpy/1.20.0/):

```bash
pip install healpy==1.20.0
```

Or from [conda-forge](https://anaconda.org/conda-forge/healpy):

```bash
conda install -c conda-forge healpy
```

## Breaking Changes

* **NumPy 2.0:** Bumped the minimum NumPy version to 2.0.0 and compiled extensions against the
NumPy 2.0 ABI. The last stable release supporting NumPy 1.x is 1.19.0.

## Summary of Changes

Here is a summary of the key changes in this release:

* **Performance:** Optimized `almxfl` for better cache locality by swapping the loop order,
resulting in a ~2-3x speedup for large datasets.
* **New Features:**
    * Added `harmonic_ud_grade` to change map NSIDE via spherical-harmonic transforms, providing an
    artifact-resistant alternative to pixel-space `ud_grade` for diffuse signals. The new API
    supports pixel-window and beam transfer corrections, direct $a_{\ell m}$ input, and API
    cross-links from `ud_grade`.
    * Added `return_ranges` parameter to `query_disc`, `query_polygon`, and `query_strip` functions
    to return pixel ranges instead of individual pixel indices, reducing memory usage from O(N) to
    O(√N) for large queries.
* **Bug Fixes:**
    * Fixed an off-by-one error in `synalm` Cℓ boundary check that caused out-of-bounds reads.
    * Fixed scalar boolean array indexing in projection functions (`mollview`, `gnomview`,
    `azeqview`) that caused corrupted masked output and assertion errors with NumPy 2.2.x and
    Python 3.14.
    * Fixed `test_rotate_alm2`: the `a_lm` initialization now includes the `m == ell` diagonal,
    matching the Fortran reference.
    * Fixed `mollview`/`projview` handling of matplotlib colormap objects so `badcolor` and
    `bgcolor` are applied consistently, and ensure `projview` masks `UNSEEN` pixels correctly.
* **Documentation and CI:**
    * Comprehensive documentation fixes including consistent HEALPix/healpy capitalization, corrected
    default values, missing parameter docs, broken RST formatting, dead Google Code URLs replaced
    with GitHub, typos, and grammar.
    * CI improvements including a new test workflow running the full test suite on Python 3.10–3.13
    with ccache, an astropy pre-release job, and building Linux wheels with manylinux_2_28 for
    x86_64/aarch64 to avoid SciPy source builds failing on missing OpenBLAS.
    * Fixed `uv pip install -e .` editable builds by recomputing pkg-config environment paths in
    `setup.py`, and added CI coverage for the uv editable install path.

For a full list of changes, please refer to the [CHANGELOG](https://github.com/healpy/healpy/blob/master/CHANGELOG.rst).