試圖返回此數組中所有年齡大於中位數的人的平均年齡

Question

我正在嘗試返回此數組中年齡大於中位數的所有人的平均年齡值。

var data = { users: [{ first_name: "Mikey", last_name: "Mouse", age: 24 
    }, { first_name: "Donald", lastName: "Duck", age: 29 }, { first_name: "Woody", lastName: "Woodpecker", age: null }, { first_name: "Bugs", lastName: "Bunny", age: 32 }] }, 
     sum = 0, 
     count = 0, 
     average; 

    data.users.forEach(function (user) { 
    if (typeof user.age === 'number') { 
     sum += user.age; 
     ++count; 
    } 
}); 

average = sum/count; 

console.log(average); 

Answer 1

在你的陣列，只有一個用戶（八哥）比平均年齡較老，所以一般也只是他的年齡，32，但這裏是代碼做任何一組用戶，給出你的問題中的數據結構。

var data = { 
    users: [ 
     { first_name: "Mikey", last_name: "Mouse", age: 24 }, 
     { first_name: "Donald", lastName: "Duck", age: 29 }, 
     { first_name: "Woody", lastName: "Woodpecker", age: null }, 
     { first_name: "Bugs", lastName: "Bunny", age: 32 } 
    ] 
}; 

// first calculate the median 
// see https://stackoverflow.com/questions/25305640/find-median-values-from-array-in-javascript-8-values-or-9-values/39639518#39639518 
function median(arr){ 
    arr = arr.sort(function(a, b){ return a - b; }); 
    var i = arr.length/2; 
    return i % 1 == 0 ? (arr[i - 1] + arr[i])/2 : arr[Math.floor(i)]; 
} 

var med = median(data.users.map(function(d){ return d.age; }).filter(function(d){ return typeof d == "number"; })); 

// now calculate the average of those users whose age is above the median 
var users_above_median = data.users.filter(function(d){ return d.age > med; }); 

function average(arr){ 
    return sum(arr)/arr.length; 
} 
function sum(arr){ 
    return arr.reduce(function(d, i){ return i + d; }); 
} 

var avg = average(users_above_median.map(function(d){ return d.age; })); 

console.log(avg);