Incorrect calculation of median

[kseo]

median([1,2,3,4]) should return 2.5, but the current implementation mistakenly returns 3.5 due to a bug in index calculation:

var median = function(data) {
    var mdarr = data.slice(0);
    mdarr.sort(function(a, b) { return a-b; });
    if (mdarr.length % 2 === 0) {
        return (mdarr[mdarr.length/2] + mdarr[mdarr.length/2 + 1]) / 2.0;
    }
    return mdarr[Math.floor(mdarr.length/2)];
};

should be

var median = function(data) {
    var mdarr = data.slice(0);
    mdarr.sort(function(a, b) { return a-b; });
    if (mdarr.length % 2 === 0) {
        return (mdarr[mdarr.length/2 - 1] + mdarr[mdarr.length/2]) / 2.0;
    }
    return mdarr[Math.floor(mdarr.length/2)];
};

[mzeinstra]

Thanks kseo,

I know that the developers behind this tool are currently all on a holiday and will most likely pick this up as soon as they are back.

In the meantime, I'm curious how are you using blockhash? In what kind of projects?

[kseo]

@mzeinstra I ported blockhash to Haskell (https://hackage.haskell.org/package/blockhash) for my personal project.

[klokan]

The same code is in python as well: https://github.com/commonsmachinery/blockhash-python/blob/master/blockhash.py#L13

[artfwo]

Fixed in master, sorry about forgetting this stupid mistake. @kseo Could you update the haskell package as well?