barbiturat
7/30/2017 - 2:21 PM

Counter for each element of array [1,2,1,2,4,2,1] //-> [[1, 1], [2, 1], [1, 2], [2, 2], [4, 1], [2, 3], [1, 3]]

Counter for each element of array [1,2,1,2,4,2,1] //-> [[1, 1], [2, 1], [1, 2], [2, 2], [4, 1], [2, 3], [1, 3]]

counter.js
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const frequency = o(nth(1), mapAccum((acc, val) => {
    const getIncreasedVal = o(inc, propOr(0, val))
    const getAccumPair = juxt([assoc(val, __, acc), pair(val)]);
    return o(getAccumPair, getIncreasedVal)(acc)
  }, {}
));

frequency([1,2,1,2,4,2,1]); //=> [[1, 1], [2, 1], [1, 2], [2, 2], [4, 1], [2, 3], [1, 3]]