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Dynamically create array of objects, from array of objects, sorted by an object property

I'm trying to match and group objects, based on a property on each object, and put them in their own array that I can use to sort later for some selection criteria. The sort method isn't an option for me, because I need to sort for 4 different values of the property.
How can I dynamically create separate arrays for the objects who have a matching property?
For example, I can do this if I know that the form.RatingNumber will be 1, 2, 3, or 4:
var ratingNumOne = [],
ratingNumTwo,
ratingNumThree,
ratingNumFour;
forms.forEach(function(form) {
if (form.RatingNumber === 1){
ratingNumOne.push(form);
} else if (form.RatingNumber === 2){
ratingNumTwo.push(form)
} //and so on...
});
The problem is that the form.RatingNumber property could be any number, so hard-coding 1,2,3,4 will not work.
How can I group the forms dynamically, by each RatingNumber?

try to use reduce function, something like this:
forms.reduce((result, form) => {
result[form.RatingNumber] = result[form.RatingNumber] || []
result[form.RatingNumber].push(form)
}
,{})
the result would be object, with each of the keys is the rating number and the values is the forms with this rating number.
that would be dynamic for any count of rating number

You could use an object and take form.RatingNumber as key.
If you have zero based values without gaps, you could use an array instead of an object.
var ratingNumOne = [],
ratingNumTwo = [],
ratingNumThree = [],
ratingNumFour = [],
ratings = { 1: ratingNumOne, 2: ratingNumTwo, 3: ratingNumThree, 4: ratingNumFour };
// usage
ratings[form.RatingNumber].push(form);

try this its a work arround:
forms.forEach(form => {
if (!window['ratingNumber' + form.RatingNumber]) window['ratingNumber' + form.RatingNumber] = [];
window['ratingNumber' + form.RatingNumber].push(form);
});
this will create the variables automaticly. In the end it will look like this:
ratingNumber1 = [form, form, form];
ratingNumber2 = [form, form];
ratingNumber100 = [form];
but to notice ratingNumber3 (for example) could also be undefined.
Just to have it said, your solution makes no sense but this version works at least.

It does not matter what numbers you are getting with RatingNumber, just use it as index. The result will be an object with the RatingNumber as indexes and an array of object that have that RatingNumber as value.
//example input
var forms = [{RatingNumber:5 }, {RatingNumber:6}, {RatingNumber:78}, {RatingNumber:6}];
var results = {};
$.each(forms, function(i, form){
if(!results[form.RatingNumber])
results[form.RatingNumber]=[];
results[form.RatingNumber].push(form);
});
console.log(results);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
HIH

// Example input data
let forms = [{RatingNumber: 1}, {RatingNumber: 4}, {RatingNumber: 2}, {RatingNumber: 1}],
result = [];
forms.forEach(form => {
result[form.RatingNumber]
? result[form.RatingNumber].push(form)
: result[form.RatingNumber] = [form];
});
// Now `result` have all information. Next can do something else..
let getResult = index => {
let res = result[index] || [];
// Write your code here. For example VVVVV
console.log(`Rating ${index}: ${res.length} count`)
console.log(res)
}
getResult(1)
getResult(2)
getResult(3)
getResult(4)

Try to create an object with the "RatingNumber" as property:
rating = {};
forms.forEach(function(form) {
if( !rating[form.RatingNumber] ){
rating[form.RatingNumber] = []
}
rating[form.RatingNumber].push( form )
})

Javascript Key/Value Pairing with Arrays

I am trying to wrap my head around how I might accomplish something like this, structurally:
var keywordDataProducts =
[
{"keyword" : "keyword1", "list" : [ "DP1", "DP2" ] },
{"keyword" : "keyword2", "list" : [ "DP1" ] }
];
But of course, without the values being hard coded. For instance, we currently loop through all the DP values (DP1, DP2, DP3, etc..) - which all have 0-M keywords. I'm trying to create an inverse lookup of that, where you can get all DPs that use a particular keyword. I have code that uses the structure above perfectly, but I just need the data to get populated more dynamically.
Do I initialize the var keywordDataProducts = []; declaration with anything in it, or define the structure of it having a keyword and a list (which is an array)? Or do you leave it as an array with nothing about it, and define that when you're adding items?
I've heard associative arrays can be used for a situation like this, but I'm not quite wrapping my head around that at the moment. I've also seen objects with {} usages, but there is no push there and I need an array of keywords, which also contains arrays of DPs (list). Thoughts?

You would do something like this, but you didn't clearly describe what the input look like and what output you're looking for.
function fn (input) {
var ouput = {};
input.forEach( function (DP) {
for (prop in DP) {
if (DP.hasOwnProperty(prop) {
if (output[prop]) {
output[prop].push(DP);
} else {
output[prop] = [DP];
}
}
}
});
return output;
}
This takes this kind of input
[{"alpha":...}, {"beta":..., "delta":...}, {"alpha":..., "gamma":...}]
and returns
{"alpha":[{"alpha":...}, {"alpha":..., "gamma":...}]}, "beta":{"beta":..., "delta":...}, "delta":{"beta":..., "delta":...}, "gamma":{"alpha":..., "gamma":...}}

I don't know how you want your output so I just made an object with each keyword as its own key for the DP values.
var data = [{dp: "dp1", keys: ["key1", "key2", "key3"]}, {dp: "dp2", keys: ["key1", "key2", "key3"]}, {dp: "dp3", keys: ["key1", "key2", "key3"]},];
function keyWordArray(arr) {
var newObj = {};
arr.forEach((obj) => {
obj.keys.forEach((keyVal) => {
if(newObj.hasOwnProperty(keyVal)){
newObj[keyVal].dp.push(obj.dp);
} else {
newObj[keyVal] = {dp:[obj.dp],};
}
});
});
return newObj;
}
document.getElementById("data").innerHTML = JSON.stringify(keyWordArray(data));
<div id="data">
</div>

You can treat objects as associative arrays, and you don't have to use "push" to add a new element.
// Create your object like this
var keywordDataProducts =
{
"keyword1" : { "list" : [ "DP1", "DP2"] },
"keyword2" : { "list" : [ "DP1" ] }
};
// Treat it like an associative array
var keyword1 = keywordDataProducts["keyword1"];
alert("keyword1 = " + keyword1.list.join(", "));
// Add to it like this
keywordDataProducts["keyword3"] = { "list" : ["DP3", "DP4"] };
// See the new object includes your new keyword
alert(JSON.stringify(keywordDataProducts));
// To iterate the keys of your object, you can do something like this
for(var item in keywordDataProducts)
{
if(keywordDataProducts.hasOwnProperty(item))
{
alert(item);
}
}
You can see the fiddle here;
https://jsfiddle.net/gksjtwr6/2/

getting distinct values from array of arrays in Javascript

My data is in the following format..
var data= [['typeName', 'valueName'], ['type1', 'value1'],
['type1', 'value2'],['type2', 'value3'],['type2', 'value4']]
I wish to transform the above data to data as below..
var resultdata=[{'typeName':'type1','valueName':['value1','value2']},
{'typeName':'type2','valueName':['value3','value4']}]
Basically I pick up distinct 'typeName' values and then group 'valueName' values by 'typeName' values.
I would preferably use only knockoutjs, lodash or underscorejs as my soln already uses them but I'm open to other solutions as well..
All help is sincerely appreciated
Thanks

I think this solution using underscore should do the trick:
var result= _.chain(data)
.rest()
.groupBy( value => value[0])
.map( (value,key) => ({ [data[0][0]]: key, [data[0][1]]: _.map(value, val => val[1])}))
.value();
This solution uses rest to skip the first item in the data array (the type descriptors). The array is then grouped by the first value in the array (the type) and the mapping returns the grouping in the required form using es6 object initializer notation.

Given the result as:
var resultdata=[
{'typeName':'type1'},{'valueName':['value1','value2']},
{'typeName':'type2'},{'valueName':['value3','value4']}
]
I'm going to call 'typeName' the category and 'valueName' the items.
Since the original data look like this:
var data= [
['typeName', 'valueName'],
['type1', 'value1'],
['type1', 'value2'],
['type2', 'value3'],
['type2', 'value4']
]
It is clear there is a pattern. The first row of data is what we'll use as labels for category and items. All the remaining data represent the values being used inside category and items.
The first step is to extract the labels:
var categoryLabel = data[0][0];
var itemLabel = data[0][1];
Next, the unique categories will need to be determined, so we'll use reduce to build an array of unique categories:
var categories = data
.filter(function(row, i) { return i > 0 }) // remove the labels
.reduce(function(arrCategories, currRow) {
// Add the current rows' category if it doesn't already exist
var currCategory = currRow[0];
if (arrCategories.indexOf(currCategory) === -1) {
return arrCategories.concat(currCategory);
}
return arrCategories;
}, [])
Now that you have a set of categories, you just need to iterate over each one to find all items that belong to it:
var valuesByCategory = {};
categories.forEach(function(category) {
// find all the data items that match the category
var items = data
.filter(function(row) { return row[0] === category; })
.reduce(function(arrItems, currRow) {
var currItem = currRow[1];
if (arrItems.indexOf(currItem) === -1) {
return arrItems.concat(currItem);
}
return arrItems;
}, []);
valuesByCategory[category] = items;
});
Now that all the data has been parsed out, the only thing left to do is build the resultant array:
var resultdata = [];
// iterate through each of the categories
categories.forEach(function(category) {
// using the category label, output an object with the label and category
var categoryObj = {};
categoryObj[categoryLabel] = category;
resultdata.push(categoryObj);
// Next, create a items object containing all the values
var itemsObj = {};
itemsObj[itemLabel] = valuesByCategory[category];
resultdata.push(itemsObj);
}
and that's it :)
The best part is that you don't need any external libraries. This is all ES2015 javascript!

Here is a lodash version of Gruff Bunnies solution:
var data= [['typeName', 'valueName'], ['type1', 'value1'], ['type1', 'value2'],['type2', 'value3'],['type2', 'value4']]
var names = data[0]
var values = _.tail(data)
console.log(JSON.stringify(
_(values)
.groupBy(0)
.map( (value, key) => ({ [names[0]]: key, [names[1]]: _.map(value, 1)}) )
.value()
))
https://jsfiddle.net/nmf1fdf5/

javascript dynamic structure with array or object

Im trying to create a structure with Javascript as follows:
var users = {
user.id: {
session.id1: session.id1,
session.id2: session.id2,
session.id3: session.id3
},
user.id2: {
session.id1: session.id1,
session.id2: session.id2,
session.id3: session.id3
},
};
What i need: add new sessions and remove them, removing okay, but how should i define object and how can i push new sessions to user obejct? That's why key is equal to value.

If you want to use session.id1 instead of something like sessionId1 :
Assign value:
users['user.id'].['session.id1'] = value;
Create object:
var users = {
'user.id': {
'session.id1': session.id1,
'session.id2': session.id2,
'session.id3': session.id3
},
'user.id2': {
'session.id1': session.id1,
'session.id2': session.id2,
'session.id3': session.id3
},
};
But I don't recommend it. If you are the only one who is gonna work with this code, it's ok.

You can first create an empty object and fill it as and when the data comes like
users[user.id] = {};
For an example:
var users = {};
var user = {id : 1}; //Data received(Just an example)
users[user.id] = {};
var session = {id1 : 1.1}; //Data received
users[user.id][session.id1] = session.id1;
console.log(JSON.stringify(users));

How about refactoring the user object to store sessions as an array and push, pop and slice them as required.
var users = [
{
id:'userid',
sessions: [
{
id: 'sessionid',
sessiondata: something
},
{
id: 'sessionid',
sessiondata: something
}
]
}];
This way to can just use normal array operators on the session array for each user.

nesting multiple level of array with associative

data = [{'name':'John'},
{'name':'Smith'},
{'name':'James'}]
how to format the above array into this
var name = {
"user": {
"name" : [{'name':'John'},
{'name':'Smith'},
{'name':'James'}]
}
}
I tried var name['name'] = data and don't know how to wrap the result. I want to wrap the result with 'user' as it assoc.

You can't assign properties as you create the object. Either first create the object and then set the property:
var name = {};
name.user = { name : data };
or create the entire object at once:
var name = { user: { name: data } };

var data = [{'name':'John'},
{'name':'Smith'},
{'name':'James'}]
var name = {
"user": {
"name" : data
}
}