Creating key/value hash out of straight array JavaScript

Question

I am trying to create a hash out of linear array in javascript. The array looks like this from which I want to create key/value hash

[13,0.011872336272725,13,0.01872336272725,13,0.0001,13,0.000660168379,13,0.006225,13,0.0000001,13,0.00925411794166,13,0.00000001,13,0.00093192461111,12,0.00007242822,12,0.9,13,0.000000005011872336272715,11,0.000001]

so I want to create a hash that will contain values like this

days= { 13: 0.011872336272725, 13: .01872336272725, 12: 0.00007242822, 11: 0.000001 } etc

to do so I trying like this

    for (var key in temphash) 
{
    var obj = temphash[key];
    for(var t = xValues.length; t >= 0; t--) 
    {
    if(obj[0] == xValues[t]) 
    {
        var keyy = xValues[t];
        if (!(keyy in days))
        {
        days[keyy] = new Array();
        }
        days[keyy].push(obj[1]); 
    }
    }
}

This xValues contains some values that I need to check if exist in temphash then only add it as key in days which will have final hash with all key and values in it.

I am pretty new in JavaScript so manage if it is silly question..;)

Your desired result is not possible because you have duplicate keys in the object. Unless you want the result as a string... — MrCode
– MrCode, Commented Apr 15, 2014 at 11:49
hmm, but is there any other convenient way to do it..like to get all values of one key on another array...or soemthing — JNI_OnLoad
– JNI_OnLoad, Commented Apr 15, 2014 at 11:50

MrCode · Accepted Answer · 2014-04-15 12:20:01Z

1

JavaScript objects can't have duplicate keys like in your desired output example.

Option 1: create an object that groups by the first number (e.g 13):

var arr = [13,0.011872336272725,13,0.01872336272725,13,0.0001,13,0.000660168379,13,0.006225,13,0.0000001,13,0.00925411794166,13,0.00000001,13,0.00093192461111,12,0.00007242822,12,0.9,13,0.000000005011872336272715,11,0.000001];
var result = {};

for(var i=0; i<arr.length; i++){
    if(i % 2 == 0){
        if(!(arr[i] in result)){
            result[arr[i]] = [];
        }
        result[arr[i]].push(arr[i+1]);
    }
}

Outputs:

{
    "11": [
        0.000001
    ],
    "12": [
        0.00007242822,
        0.9
    ],
    "13": [
        0.011872336272725,
        0.01872336272725,
        0.0001,
        0.000660168379,
    ]
    ...
}

You can then easily get all 13's by doing:

console.log( result['13'] );

Option 2: build an array of objects instead:

var arr = [13,0.011872336272725,13,0.01872336272725,13,0.0001,13,0.000660168379,13,0.006225,13,0.0000001,13,0.00925411794166,13,0.00000001,13,0.00093192461111,12,0.00007242822,12,0.9,13,0.000000005011872336272715,11,0.000001];

var result = [];
var obj;

for(var i=0; i<arr.length; i++){
    if(i % 2 == 0){
        obj = {}
        obj[arr[i]] = arr[i+1];
        result.push(obj);
    }
}

The result looks like:

[
    {
        "13": 0.011872336272725
    },
    {
        "13": 0.01872336272725
    },
    {
        "13": 0.0001
    },
    ...
]

To find all values for a given key, you can do:

var target = 13; // search for what?
for(var j=0; j<result.length; j++){
    if(target in result[j]){
        console.log( 'found target, value is ' + result[j][target] );   
    }
}

edited Apr 15, 2014 at 12:20

answered Apr 15, 2014 at 12:04

MrCode

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6 Comments

JNI_OnLoad Over a year ago

so if I want to access all values for say "13" I need loop for just arr[13] wouild work...

MrCode Over a year ago

@user1618 added another method if you want to group them.

JNI_OnLoad Over a year ago

Thanks, I just try and understand it, will accept the answer soon

JNI_OnLoad Over a year ago

it is creating wrong JSON string in second case which is like this [ { "13,0.0000005011872336272725":[ 13, "0.0000005011872336272725" ] }, { "13,0.0000001":[ 13, "0.0000001" ] }, { "13,0.0000005011872336272725":[ 13, "0.0000005011872336272725" ] },

MrCode Over a year ago

@user1618 which method are you using to get that? Can you create a jsfiddle to demo it?

|

AlexCV · Accepted Answer · 2014-04-15 12:20:37Z

0

You can try this format for a key/(array values) result:

var i, key, value, obj;
for (i = 0; i < array.length; i += 2) {
    key = array[i];
    value = array[i+1];
    if (!obj[key]) {
        obj[key] = [];
    }
    obj[key].push(value);
}

result:

{
    13: [0.011872336272725, 0.01872336272725, ...],
    12: [0.00007242822, ...],
    ...
}

You should be careful about the array length and add some checks for the integrity of the data.

edited Apr 15, 2014 at 12:20

answered Apr 15, 2014 at 12:12

AlexCV

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Comments

JNI_OnLoad · Accepted Answer · 2014-04-16 07:58:49Z

Thanks to @MrCode for guiding me to make it work. The answers above are correct but minor issue in creating JSON string exactly what I want, so I am updating the answer for future references....

 function find(arr) {
    var result = {};

for(var key in arr){

    var obj = arr[key];
    if(!(obj[0] in result)){
        result[obj[0]] = [];
    }
    result[obj[0]].push(obj[1]);

}

} This will end up creating something like this

{
"11": [
    0.000001
],
"12": [
    0.00007242822,
    0.9
],
"13": [
    0.011872336272725,
    0.01872336272725,
    0.0001,
    0.000660168379,
]
...

} While in above solutions the created json was having key something like this "13,0.011872336272725" in between

Now data can be accessed easily with key such as console.log(result[13])

I hope It woul;d be helpful for someone

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