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..;)

Answer 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] ); } } 

Answer 2

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.

Answer 3

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