Extracting scores from HotCRP

USENIX conferences use this tool called HotCRP to manage the conference review process. Like other systems, you rate papers on a numeric scale (1-5). When you ask for a summary of the papers, the system displays a cute little graphic of how many people have chosen each rating (and even a cute little mouseover that displays the mean and SD), but once you have more than a few papers to look, it's a bit inconvenient to get a sense of the distribution. Maybe the PC chairs have a tool, but PC members don't. Luckily, it's easy to extract it from the HTML source. Here's a Perl script that will suck out the scores and compute the mean:

#!/usr/bin/perl
while(){
    next unless /GenChart\?v=([\d,]+)/;
    
    @scores=split(/,/,$1);
    
    $sum = 0;
    $ct = 0;

    for($i=0; $i<=$#scores; $i++){
	$sum += ($i + 1) * $scores[$i];
	$ct += $scores[$i];
    }

    $mean = $sum / $ct;
    
    print "$mean\n";
}

You just do save as¹ and shove the file into the script on stdin. Extracting standard deviations and the name of the paper are left as exercises for the reader.

^1. Note: you need to save as source not a complete Web page/directory. Otherwise the browser helpfully saves the images and rewrites the links to point to your local disk, which breaks everything. Took me a while to figure out what the heck was going on with that one.