js:riak mr example

ex-largest-day.js

{
  "inputs":"goog",
  "query":[
    {"map":{
      "language":"javascript",
      "source":
        "function(value, keyData, arg) {
          var data = Riak.mapValuesJson(value)[0];
          var month = value.key.split('-').slice(0,2).join('-');
          var volume = data.Volume;
          var adj_close = data['Adj. Close'];
          var obj = {};
          obj[month] = volume * adj_close;
          return [ obj ];
        }"
      }
    },
    {"reduce":{
      "language":"javascript",
      "source":
        "function(values, arg) {
          return [ values.reduce(function(acc, item) {
            for (var month in item) {
              if (acc[month]) {
                acc[month] = (acc[month] < item[month]) ? item[month] : acc[month];
              } else {
                acc[month] = item[month];
              }
            }
            return acc;
          })];
        }",
      "keep":true}
    },
    {"reduce":{
      "language":"javascript",
      "source":
        "function(values, arg) {
          var maxtrade = { day:'', value:0};
          for (var key in values[0]){
            if (maxtrade.value < values[0][key]) {
              maxtrade.value = values[0][key];
              maxtrade.day = key;
            }
          }
          return [maxtrade];
        };",
      "keep":true}
    }
  ]
}