High Performance Computing & AI
Practical notes on Python, JupyterHub, Kubernetes and AI for science — from the San Diego Supercomputer Center.
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Interactive figures in the browser - CMB power spectra
For a long time I've been curious about trying out d3.js , the javascript plotting library which is becoming the standard for interactive plotting in the browser.
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Planck CTP angular power spectrum ell binning
Planck released a binning of the angular power spectrum in the Explanatory supplement, unfortunately the file is in PDF format, non easily machine-readable: http://www.sciops.esa.int/wikiSI/planckpla/index.php?title=Frequencymapsangularpowerspectra&instance=PlanckPublicPLA So here is a csv version: https://gist.github.com/zonca/6288439 Follows embedded gist.
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HEALPix map of the Earth using healpy
HEALPix maps can also be used to create equal-area pixelized maps of the Earth, RGB colors are not supported in healpy, so we need to convert the image to colorscale. The best user case is for using spherical harmonic transforms, e.g. apply a smoothing filter, in this case HEALPix/healpy tools are really efficient.
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Export google analytics data via API with Python
Fun weekend hacking project: export google analytics data using the google APIs. Clone the latest version of the API client from: https://code.google.com/p/google-api-python-client there is an example for accessing analytics APIs in the samples/analytics folder, but you need to fill in clientsecrets.json.
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Processing sources in Planck maps with Hadoop and Python
Purpose The purpose of this post is to investigate how to process in parallel sources extracted from full sky maps, in this case the maps release by Planck, using Hadoop instead of more traditional MPI-based HPC custom software.
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How to use the IPython notebook on a small computing cluster
The IPython notebook is a powerful and easy to use interface for using Python and particularly useful when running remotely, because it allows the interface to run locally in your browser, while the computing kernel runs remotely on the cluster.
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IPython parallell setup on Carver at NERSC
IPython parallel is one of the easiest ways to spawn several Python sessions on a Supercomputing cluster and process jobs in parallel. On Carver, the basic setup is running a controller on the login node, and submit engines to the computing nodes via PBS.
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Simple Mixin usage in python
One situation where Mixins are useful in Python is when you need to modify a method of similar classes that you are importing from a package.
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Noise in spectra and map domain
Spectra NET or $\sigma$ is the standard deviation of the noise, measured in mK/sqrt(Hz), typical values for microwave amplifiers are 0.2-5. This is the natural unit of the amplitude spectra (ASD), therefore the high frequency tail of the ASD should get to the expected value of the NET.
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Basic fork/pull git workflow
Typical simple workflow for a (github) repository with few users.
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Interactive 3D plot of a sky map
update May 2024: See the new version of this tutorial Mayavi is a Python package from Enthought for 3D visualization, here a simple example of creating a 3D interactive map starting from a HEALPix pixelization sky map:
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How to cite HDF5 in bibtex
here the bibtex entry: reference: https://www.hdfgroup.org/solutions/hdf5/
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Compile healpix C++ to javascript
Compile C++ -> LLVM with clang Convert LLVM -> Javascript: https://github.com/kripken/emscripten/wiki/Tutorial
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Elliptic beams, FWHM and ellipticity
The relationship between the Full Width Half Max, FWHM (min, max, and average) and the ellipticity is: FWHM = sqrt(FWHMmin FWHMmax) e = FWHMmax/FWHMmin
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Ubuntu PPA for HEALPix and healpy
HEALPix C, C++ version 3.00 and healpy version 1.4.1 are now available in a PPA repository for Ubuntu 12.04 Precise and Ubuntu 12.10 Quantal.