python
135 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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PySM: produce CAR output at the smoothing stage
PySM 3 only builds HEALPix skies. Here is how to produce CAR pixelization output at the smoothing stage with a single spherical harmonic transform, and a validation against the smooth-then-reproject route.
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Python for HPC at SDSC Summer Institute 2026
I updated the Python for HPC session I taught at the SDSC Summer Institute 2026 (August 7, 2026). The material was heavily rewritten for this year - a substantial rework, not a refresh of the 2025 version.
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Deploy the Dask Operator for Kubernetes on Jetstream2 and access it from JupyterHub
This post describes how to deploy the Dask Operator for Kubernetes alongside a Helm-based JupyterHub installation on a Jetstream2 Kubernetes cluster (Magnum). The Operator provides a Kubernetes-native way to create and manage Dask clusters via custom resources, simplifying multi-tenant setups.
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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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PySM 3.4.6 released: FLAMINGO kSZ models and c1 documentation
A practical introduction to the new FLAMINGO kinetic SZ presets and documented c1 cosmology in PySM 3.4.6.
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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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PySM 3.4.5: HalfDome TSZ model, scipy pin removed, Python 3.9 dropped
PySM 3.4.5 is now available on PyPI and GitHub. Changes in this release:
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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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Do you need JupyterHub for your workshop? JupyterLite runs Python in the browser
You're organizing a Python workshop or teaching a class that uses Jupyter notebooks. The first question that comes up is almost always the same: how do I get everyone running notebooks without spending an hour on installation?
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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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SPT-3G D1 high-ℓ CMB power spectra vs. Planck 2018
Load and compare the SPT-3G D1 high-ell TT power spectra with the Planck 2018 CMB power spectrum, illustrating primary vs. secondary CMB anisotropies.
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Send email using UCSD SMTP with a Gmail-based address
If you have a GMAIL-based UCSD email address and need to send email programmatically or via an email client using SMTP, you can use Google's SMTP servers.
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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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PySM 3.4.4 released with new SZ models and NumPy 2 support
PySM 3.4.4 is now available both on PyPI and on conda-forge. This release is mostly about extending the Sunyaev-Zeldovich model suite and making sure PySM works cleanly with NumPy 2.