Calculate percentage with lodash

Question

I have data like:

var data = 
    [{
        "date":"1-1-2013",
        "answer":"yes"
    },{
        "date":"1-1-2013",
        "answer":"no"
    },{
        "date":"2-1-2013",
        "answer":"no"
    },{
        "date":"2-1-2013",
        "answer":"no"
    },{
        "date":"2-1-2013",
        "answer":" "       //this is not answered!
    },,{
        "date":"2-1-2013",
        "answer":"no"       
    }];

I need to return[array] percentages of responses for that day(groupedBy) which have a value of “yes” for the “answer”.

For above the result is: [50, 0...]

I have written this below code, it works but i believe it can be simplified a lot.

var freshData =  _.map(data,function(key){
    if (key.answer == "") return false;
    return key;

});

var reducedData = _.filter(freshData, function(n) {
    return n != false;
});

var groups = _.groupBy(reducedData, function(value){
        return value.date + '#' + value.answer;
});

var result = _.map(groups,function(key){
    if (key[0].answer == "") return false;
    return {
        date : key[0].date,
        answer : key[0].answer,
        length :key.length
    };
});

var result2 = _.chunk(result,2);

var result3 =  _.map(result2,function(key){
    return {
        date:key[0].date,
        yes:key[0].length,
        no:key[1].length,
        percentage : (key[1].length/(key[0].length + key[1].length) * 100)
    }
});

var result4 =  _.map(result3,function(key){
return  key.percentage;
});

console.log(result4);

I need to use lodash. Thanks.

Answer 1

solution with lodash:

var data = [{
    "date": "1-1-2013",
        "answer": "yes"
}, {
    "date": "1-1-2013",
        "answer": "no"
}, {
    "date": "2-1-2013",
        "answer": "no"
}, {
    "date": "2-1-2013",
        "answer": "no"
}, {
    "date": "2-1-2013",
        "answer": " " //this is not answered!
}, {
    "date": "2-1-2013",
        "answer": "no"
}];

//var grouped = _.groupBy(data, 'date');
var all = _.map(_.groupBy(data, 'date'), function (item, key) {
    console.log(key);
    var size = item.length,
        obj={};
    var positiveCount = _.countBy(item, function (i) {
        return i.answer == "yes" ? "yes" : "no";
    });
    var percentagePossitive = (positiveCount.yes / size) * 100;
    obj[key] = percentagePossitive || 0;
    return obj;
});

console.log(all)

Answer 2

Create a lodash chain, use _.groupBy() to get a dates map, and then reduce it to percentages:

function getNumOfYes(data) {
  return _(data).groupBy('date').reduce(function(percentage, answers) {
    var numOfYes = _.countBy(answers, 'answer').yes || 0;
    percentage.push(numOfYes / answers.length * 100);
    return percentage;
  }, []);
}

var data = [{
  "date": "1-1-2013",
  "answer": "yes"
}, {
  "date": "1-1-2013",
  "answer": "no"
}, {
  "date": "2-1-2013",
  "answer": "no"
}, {
  "date": "2-1-2013",
  "answer": "no"
}, {
  "date": "2-1-2013",
  "answer": " " //this is not answered!
}, , {
  "date": "2-1-2013",
  "answer": "no"
}];

var numOfYes = getNumOfYes(data);

console.log(numOfYes);

document.getElementById('results').innerText = JSON.stringify(numOfYes);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

<pre id="results"></pre>

Answer 3

You can utilize a temporary object for counting and returns an array of objects with date and percentage.

var data = [{
        "date": "1-1-2013",
        "answer": "yes"
    }, {
        "date": "1-1-2013",
        "answer": "no"
    }, {
        "date": "2-1-2013",
        "answer": "no"
    }, {
        "date": "2-1-2013",
        "answer": "no"
    }, {
        "date": "2-1-2013",
        "answer": " "       //this is not answered!
    }, , {
        "date": "2-1-2013",
        "answer": "no"
    }];

function getPercentage(data) {
    var obj = {};
    data.forEach(function (a) {
        if (~['yes','no'].indexOf(a.answer)) {                
            obj[a.date] = obj[a.date] || { yes: 0, no: 0 };
            obj[a.date][a.answer]++;
        }
    });
    return Object.keys(obj).map(function (k) {
        return { 
            date: k,
            percent: obj[k].yes * 100 / (obj[k].yes + obj[k].no)
        };
    });
}
document.write('<pre>' + JSON.stringify(getPercentage(data), 0, 4) + '</pre>');

Answer 4

Answer in JS fiddle (check console)

Note, I've used Lodash, but you don't really need it to this :-)

var sortedResults = {}; // create empty object

/**
 * sort all the answers on date
 */
_.map(data, function(val){
    if(typeof val !== 'undefined'){ // check if not undefined
        if(val.answer==='yes' || val.answer==='no'){ // should be yes or no
            if (typeof(sortedResults[val.date]) === 'undefined') {
                sortedResults[val.date] = []; // if data is not available, add it as an array
            }
            sortedResults[val.date].push(val.answer); // push the answer to the array
        }
    }
});

/**
 * Calculate the percentages of 'yes'
 */
_.map(sortedResults, function(val, key){
    var percentage    = val.length, // get total length
        percentageYes = 0; // before map function percentage = 0
    _.each(val, function(singleVal){
        if(singleVal === 'yes'){ percentageYes++; }
    });
    sortedResults[key] = { yesPercent: percentageYes / percentage * 100 };
});

/**
 * Percentage is available in sortedResults;
 */
console.log(sortedResults);