errors in the  estimation. In contrast to previous works, our  estimation has no systematic trend with galactic parameters such as M$_{\star}$, $g-r$ and SFR. We present a catalog of  estimates for more than half a million galaxies in the SDSS, of which $\sim$ 150,000 galaxies have a secure selection parameter with average scatter in the  estimation of 0.22 dex.'
author:
- |
    Hossen Teimoorinia$^1$, Sara L. Ellison$^1$ & David R. Patton$^2$\
    $^1$ Department of Physics & Astronomy, University of Victoria, Finnerty Road, Victoria, British Columbia, V8P 1A1, Canada.\
    $^{2}$Department of Physics and Astronomy, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada.\
title: 'Pattern recognition in the ALFALFA.70 and Sloan Digital Sky Surveys: A catalog of $\sim$ 500,000 HI gas fraction estimates based on artificial neural networks.'
---

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galaxies: fundamental parameters -galaxies: evolution - methods: data analysis- methods: statistical- Astronomical data bases: surveys

introduction
============

Neutral hydrogen plays an important role in the fuelling pipeline for star formation activity in galaxies. The study of HI can therefore provide insights into some of the main physical processes that drive galaxy evolution. To this end, numerous surveys (see Giovanelli & Haynes 2015 for a recent review) have been conducted 