example-mongo-operations.js

var dataOriginal = db.getCollection('SummaryUtilization').find({
    MonthYear: 62016
}).toArray()

var dataGroupedByMonthYearAndEmp = {}
dataOriginal.forEach(function (eachData) {
    
    // ========= calculate percentage
    
    eachData.Percentage = eachData.SumChargeable / (eachData.CoreHours - eachData.PublicHours)
    if (!isFinite(eachData.Percentage) || isNaN(eachData.Percentage)) eachData.Percentage = 0
    
    // ========= group data
    
    var key = String(eachData.MonthYear) + " - " + String(eachData.EmpCode)
    var rows = []
    
    if (dataGroupedByMonthYearAndEmp.hasOwnProperty(key)) {
        rows = dataGroupedByMonthYearAndEmp[key]
    }
    
    rows.push(eachData)
    dataGroupedByMonthYearAndEmp[key] = rows
})

for (var key in dataGroupedByMonthYearAndEmp) {
    var rows = dataGroupedByMonthYearAndEmp[key]
    var sampleData = rows[0]
    
    var percentagesWithCNUEquals1 = []
    
    rows.forEach(function (eachRow) {
        if (eachRow.C_n_u === 1) {
            percentagesWithCNUEquals1.push(eachRow.Percentage)
        }
    })
    
    if (percentagesWithCNUEquals1.length == 0) {
        sampleData.Percentage = 0
    } else if (percentagesWithCNUEquals1.length == 1) {
        sampleData.Percentage = percentagesWithCNUEquals1[0]
    } else {
        sampleData.Percentage = percentagesWithCNUEquals1.reduce(function (d, e) { return d + e }, 0) / percentagesWithCNUEquals1.length
    }
    
    db.getCollection("EXAMPLE").save(sampleData)
}