ColdPress: Efficient Quantile-Based Compression of Photometric Redshift PDFs

Abstract: ColdPress is a Python module that compresses photometric redshift probability distribution functions (PDFs) by encoding quantiles of their cumulative distribution. For a fixed packet size (the default is 80 bytes per PDF), ColdPress attains a reconstruction accuracy comparable to the sparse-basis representation method implemented in the pdf_storage module of Carrasco-Kind & Brunner (2014), yet reduces the computational cost by a factor of ~7000. I describe the implementation and quantify its compression speed and reconstruction accuracy in comparison to pdf_storage for real-life PDFs from two different photometric redshift codes. ColdPress is free software, available at https://github.com/ahc-photoz/coldpress-project.