bigram text

gistfile1.js

function bigramText(arr) {
    return arr.reduce(bigramArray);
}

function bigramArray(acc, word, i, arr) {
    if (1 === i) {
        acc = {last: acc, out: {}};
    }
    var out = acc.out;
    var last = acc.last;

    out[last] = out[last] || {};
    out[last][word] = out[last][word] + 1 || 1;

    acc.last = word;
    acc.out = out;

    if (i === arr.length - 1) {
        return acc.out;
    }

    return acc;
}