healpy
37 posts
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SLIC superpixels on the HEALPix grid
A recent healpy issue proposes a slic function that generates superpixels on the HEALPix grid, adapting the SLIC algorithm to the sphere, with a complete working implementation attached. This post is what I found testing it.
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healpy 1.20.1: last release with macOS 14 wheels
The healpy 1.20.1 release includes bug fixes and is the final release to provide macOS 14 arm64 wheels before the GitHub runner retirement.
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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.
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healpy 1.20.0b1 beta — harmonic_ud_grade for artifact-safe map downgrading
pip install --pre healpy==1.20.0b1 harmonicudgrade changes map NSIDE through spherical-harmonic transforms with pixel-window and beam transfer corrections following Eq. 1 of Planck 2015 X (arXiv:1502.01588).
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healpy harmonic_ud_grade vs skytools change_resolution: A Comparison
A comparison of healpy.harmonic_ud_grade and skytools.change_resolution for HEALPix map resolution changes, highlighting API differences, beam/pixel-window support, direct alm input, and agreement levels.
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harmonic_ud_grade vs ud_grade: A Focused Comparison
harmonic_ud_grade vs ud_grade A Focused Comparison.
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Why 3 pixels per beam? The mathematics of HEALPix resolution matching
Exploring why the Planck convention uses FWHM = 3 x pixel size for harmonic-space map downgrading, with equations from the literature and simulated demonstrations.
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Release of healpy 1.19.0
I am pleased to announce the release of healpy 1.19.0. This release includes a large number of fixes and improvements, many of which were made possible by adopting an "agentic" workflow. As detailed in my recent blog post, I have been using AI coding agents to help triage and fix issues, allowing us to close old bugs and improve the codebase significantly.
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Healpy blm_gauss breaking change analysis
Analyzing the breaking change in healpy's blm_gauss function (1.18.1 to 1.19.0) and its impact on Gaussian beam coefficients.
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healpy 1.18.1 released
Just released healpy 1.18.1, this version includes important bug fixes, please test and open issues at Major improvements in this release:
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Generate sample Cosmology data for Cheap and FAIR data portal with PySM
This notebook generates some figures of Galactic and Extra-Galactic emissions using PySM. Mostly for displaying purposes.
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Run (part of) healpy in the browser with pyodide
Thanks to the help of @VeerioSDSC and Rick Wagner, I have been able to run part of healpy in the browser. For now only tested reading FITS maps and plotting with projview.
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2024-05-20-HEALPix-in-Megapixels
How many megapixels is a HEALPix map? python !pip install healpy
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Generate figures for PySM emissions
This notebook generates some figures of Galactic and Extra-Galactic emissions using PySM. Mostly for displaying purposes.
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Gzipping or not gzipping HEALPix maps
HEALPix maps are generally stored in FITS format, they can be Gzipped to save disk space. Reading gzipped maps is natively supported in healpy, however, it takes longer because maps are uncompressed on the fly.