Develop Reference

Finding objects in a nested array along with their position

I've taken the following sample from a different question. And I am able to identify the object. But I also need to find our the position of that object. For example:
var arr = [{
Id: 1,
Categories: [{
Id: 1
},
{
Id: 2
},
]
},
{
Id: 2,
Categories: [{
Id: 100
},
{
Id: 200
},
]
}
]
If I want to find the object by the Id of the Categories, I can use the following:
var matches = [];
var needle = 100; // what to look for
arr.forEach(function(e) {
matches = matches.concat(e.Categories.filter(function(c) {
return (c.Id === needle);
}));
});
However, I also need to know the position of the object in the array. For example, if we are looking for object with Id = 100, then the above code will find the object, but how do I find that it's the second object in the main array, and the first object in the Categories array?
Thanks!

Well, if every object is unique (only in one of the categories), you can simply iterate over everything.
var arr = [{
Id: 1,
Categories: [{Id: 1},{Id: 2}]
},
{
Id: 2,
Categories: [{Id: 100},{Id: 200}]
}
];
var needle = 100;
var i = 0;
var j = 0;
arr.forEach(function(c) {
c.Categories.forEach(function(e) {
if(e.Id === needle) {
console.log("Entry is in position " + i + " of the categories and in position " + j + " in its category.");
}
j++;
});
j = 0;
i++;
});

function findInArray(needle /*object*/, haystack /*array of object*/){
let out = [];
for(let i = 0; i < haystack.lenght; i++) {
if(haystack[i].property == needle.property) {
out = {pos: i, obj: haystack[i]};
}
}
return out;
}
if you need the position and have to filter over an property of the object you can use a simple for loop. in this sample your result is an array of new object because there can be more mathches than 1 on the value of the property.
i hope it helps

Iterate over the array and set index in object where match found
var categoryGroups = [{
Id : 1,
Categories : [{
Id : 1
}, {
Id : 2
},
]
}, {
Id : 2,
Categories : [{
Id : 100
}, {
Id : 200
},
]
}
]
var filterVal = [];
var needle = 100;
for (var i = 0; i < categoryGroups.length; i++) {
var subCategory = categoryGroups[i]['Categories'];
for (var j = 0; j < subCategory.length; j++) {
if (subCategory[j]['Id'] == findId) {
filterVal.push({
catIndex : i,
subCatIndex : j,
id : needle
});
}
}
}
console.log(filterVal);

Here is solution using reduce:
var arr = [{ Id: 1, Categories: [{ Id: 1 }, { Id: 2 }, ] }, { Id: 2, Categories: [{ Id: 100 }, { Id: 200 }, ] } ]
const findPositions = (id) => arr.reduce((r,c,i) => {
let indx = c.Categories.findIndex(({Id}) => Id == id)
return indx >=0 ? {mainIndex: i, categoryIndex: indx} : r
}, {})
console.log(findPositions(100)) // {mainIndex: 1, categoryIndex: 0}
console.log(findPositions(1)) // {mainIndex: 0, categoryIndex: 0}
console.log(findPositions(200)) // {mainIndex: 1, categoryIndex: 1}
console.log(findPositions(0)) // {}

Beside the given answers with fixt depth searh, you could take an recursive approach by checking the Categories property for nested structures.
function getPath(array, target) {
var path;
array.some(({ Id, Categories = [] }) => {
var temp;
if (Id === target) {
path = [Id];
return true;
}
temp = getPath(Categories, target);
if (temp) {
path = [Id, ...temp];
return true;
}
});
return path;
}
var array = [{ Id: 1, Categories: [{ Id: 1 }, { Id: 2 },] }, { Id: 2, Categories: [{ Id: 100 }, { Id: 200 }] }];
console.log(getPath(array, 100));
.as-console-wrapper { max-height: 100% !important; top: 0; }

Get Unique Key-Value count as an object

I've got the following response from the server:
I want to get the unique key with the occurrence count.
In the following format:
0:{"name":"physics 1","count":2}
1:{"name":"chem 1","count":6}
I've already checked How to count the number of occurrences of each item in an array? but that is not I want.

Here is an es6 solution.
const data = [{
id: 0,
name: 'physics 1',
questionId: 1,
questionNr: 1
}, {
name: 'physics 1',
}, {
name: 'chem 1',
}, {
name: 'chem 1',
}, {
name: 'chem 2',
}];
const grouped = data.reduce((groups, cur) => {
const key = cur.name;
groups[key] = (groups[key] || 0) + 1;
return groups;
}, {});
const result = Object.keys(grouped).map(key => ({name: key, count: grouped[key]}));
console.log(result);

You could do it this way:
var source = [
{'section_name': 'test1'},
{'section_name': 'test2'},
{'section_name': 'test1'},
];
var temp = {};
for (var i = source.length - 1; i >= 0; i--) {
var key = source[i].section_name;
if (!temp[key]) {
temp[key] = 0;
}
temp[key] += 1;
}
var keys = Object.keys(temp);
var result = [];
for (var i = keys.length - 1; i >= 0; i--) {
var key = keys[i];
result.push({"name":key,"count":temp[key]});
}
console.log(result);

use this function this uses map and filter
t.reduce((f,l)=>{
var k=f.filter(elem=>elem.section_name==l.section_name);
if(k.length==1) k[0].count++;
else f.push({section_name:l.section_name,count:1})
return f;
},[] )
you can check this against this to verify
var t=[{section_name:"Physics"},{section_name:"Physics"},{section_name:"Chemistry"},{section_name:"Chemistry"},{section_name:"Physics"}]

Javascript Fill array with missing object and value

I have an array like bellow each index contains different set of objects,I want to create an uniformal data where object missing in each index will with Value:0 ,
var d = [
[
{axis:"Email",value:59,id:1},
{axis:"Social Networks",value:56,id:2},
],
[
{axis:"Sending Money",value:18,id:6},
{axis:"Other",value:15,id:7},
]
];
how can I get an array like bellow using above above array
var d = [
[
{axis:"Email",value:59,id:1},
{axis:"Social Networks",value:56,id:2},
{axis:"Sending Money",value:0,id:6},
{axis:"Other",value:0,id:7},
],
[
{axis:"Email",value:0,id:1},
{axis:"Social Networks",value:0,id:2},
{axis:"Sending Money",value:18,id:6},
{axis:"Other",value:15,id:7},
]
];

There are two functions:
getAllEntries that find all objects and stores them into a variable accEntries. Then accEntries is used to search for all occurrences in a sub-array of d. This whole process is done in checkArray.
checkArray is used to fetch all found and not-found entries in d. Both Arrays (found and not-found) are then used to build a new sub-array that contains either found entries with certain values and/or not-found entries with values of 0.
Hope this helps:
var d = [
[
{
axis: 'Email',
value: 59,
id: 1
},
{
axis: 'Social Networks',
value: 56,
id: 2
},
],
[
{
axis: 'Sending Money',
value: 18,
id: 6
},
{
axis: 'Other',
value: 15,
id: 7
},
]
];
function getAllEntries(array) {
var uniqueEntries = [];
array.forEach(function (subarray) {
subarray.forEach(function (obj) {
if (uniqueEntries.indexOf(obj) === - 1) uniqueEntries.push(obj);
});
});
return uniqueEntries;
}
function checkArray(array, acceptedEntries) {
var result = [];
array.forEach(function (subArray) {
var subResult = [];
var foundEntries = [];
subArray.forEach(function (obj) {
if (foundEntries.indexOf(obj.axis) === - 1) foundEntries.push(obj.axis);
});
var notFound = acceptedEntries.filter(function (accepted) {
return foundEntries.indexOf(accepted.axis) === - 1;
});
foundEntries.forEach(function (found) {
subArray.forEach(function (obj) {
if (obj.axis === found) subResult.push(obj);
});
});
notFound.forEach(function (notfound, index) {
subResult.push({
axis: notfound.axis,
value: 0,
id: notfound.id
});
});
result.push(subResult);
});
return result;
}
var accEntries = getAllEntries(d);
var result = checkArray(d, accEntries);
console.log(result);

You can loop over the array to find all the unique objects and then again loop over to push the values that are not present comparing with the array of objects of unique keys.
You can use ES6 syntax to find if an object with an attribute is present like uniKeys.findIndex(obj => obj.axis === val.axis); and the to push with a zero value use the spread syntax like d[index].push({...val, value: 0});
Below is the snippet for the implementation
var d = [
[
{axis:"Email",value:59,id:1},
{axis:"Social Networks",value:56,id:2},
],
[
{axis:"Sending Money",value:18,id:6},
{axis:"Other",value:15,id:7},
{axis:"Social Networks",value:89,id:2},
]
];
var uniKeys = [];
$.each(d, function(index, item) {
$.each(item, function(idx, val){
const pos = uniKeys.findIndex(obj => obj.axis === val.axis);
if(pos == - 1) {
uniKeys.push(val);
}
})
})
$.each(d, function(index, item) {
var temp = [];
$.each(uniKeys, function(idx, val){
const pos = item.findIndex(obj => obj.axis === val.axis);
if(pos == - 1) {
d[index].push({...val, value: 0});
}
})
})
console.log(d);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

How about a short shallowCopy function (Object.assign is not available in IE) and otherwise less than 10 new lines of code?
var d = [
[
{axis:"Email",value:59,id:1},
{axis:"Social Networks",value:56,id:2}
],
[
{axis:"Sending Money",value:18,id:6},
{axis:"Other",value:15,id:7}
]
];
var newD_0 = [shallowCopy(d[0][0]), shallowCopy(d[0][1]), shallowCopy(d[1][0]), shallowCopy(d[1][1])];
var newD_1 = [shallowCopy(d[0][0]), shallowCopy(d[0][1]), shallowCopy(d[1][0]), shallowCopy(d[1][1])];
newD_0[2].id = 0;
newD_0[3].id = 0;
newD_1[0].id = 0;
newD_1[1].id = 0;
d = [newD_0, newD_1];
function shallowCopy(obj) {
var copy = {};
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
copy[key] = obj[key];
}
}
return copy;
}
console.log(JSON.stringify(d));
RESULT:
[
[
{
"axis":"Email",
"value":59,
"id":1
},
{
"axis":"Social Networks",
"value":56,
"id":2
},
{
"axis":"Sending Money",
"value":18,
"id":0
},
{
"axis":"Other",
"value":15,
"id":0
}
],
[
{
"axis":"Email",
"value":59,
"id":0
},
{
"axis":"Social Networks",
"value":56,
"id":0
},
{
"axis":"Sending Money",
"value":18,
"id":6
},
{
"axis":"Other",
"value":15,
"id":7
}
]
]

Find duplicate value in array of objects and merge some duplicate key and value

I have two arrays of objects
array = [
{
"id_0":356,
"name":"India",
"key1":150
},
{
"id_0":356,
"name":"India",
"key2":200
},
{
"id_0":748,
"name":"Swaziland",
"key1":140
},
{
"id_0":748,
"name":"Swaziland",
"key2":180
}
]
I am trying to find the duplicate id_0 in array of objects and merge the duplicate object of key2 and value.
I want the result to be:
array = [
{
"id_0":356,
"name":"India",
"key1":150,
"key2":200
},
{
"id_0":748,
"name":"Swaziland",
"key1":140,
"key2":180
}
]
How to find the duplicate value and merge the duplicate key and value in array?

You can use Array.prototype.reduce() to reduce your array as you need.
Duplicate item can be merged using Object.assign().
var array = [
{ 'id_0': 356, 'name': 'India', 'key1': 150 },
{ 'id_0': 356, 'name': 'India', 'key2': 200 }
];
var result = array.reduce(function(prev, item) {
var newItem = prev.find(function(i) {
return i.id_0 === item.id_0;
});
if (newItem) {
Object.assign(newItem, item);
} else {
prev.push(item);
}
return prev;
}, []);
console.log(result);
Object.assign is part of ES6. If it does not work for you, just replace it with:
for (var attrname in item) {
newItem[attrname] = item[attrname];
};

Try this fiddle
var array = [
{
"id_0":356,
"name":"India",
"key1":150
},
{
"id_0":356,
"name":"India",
"key2":200
},
{
"id_0":356,
"name2":"china",
"key2":200
}
]
function mergeArray( arr )
{
var outputObj = {};
for ( var counter = 0; counter < arr.length; counter++ )
{
var obj = arr[ counter ];
for( var key in obj )
{
if ( !outputObj[ key ] )
{
outputObj[ key ] = obj[ key ];
}
}
}
return outputObj;
}
console.log( mergeArray( array ) );
Edited the fiddle to suit your 'UPDATED' requirement
var array = [
{
"id_0":356,
"name":"India",
"key1":150
},
{
"id_0":356,
"name":"India",
"key2":200
},
{
"id_0":400,
"name2":"china",
"key2":200
},
{
"id_0":400,
"name2":"china",
"key2":200
}
]
function mergeArray( arr )
{
var outputObj = {};
for ( var counter = 0; counter < arr.length; counter++ )
{
var obj = arr[ counter ];
for( var key in obj )
{
if ( !outputObj[ key ] )
{
outputObj[ key ] = obj[ key ];
}
}
}
return outputObj;
}
function collateArray( arr )
{
var outputObj = {};
var result = [];
for ( var counter = 0; counter < arr.length; counter++ )
{
var obj = arr[ counter ];
var id_0value = obj[ "id_0" ];
if ( !outputObj[ id_0value ] )
{
outputObj[ id_0value ] = [];
}
outputObj[ id_0value ].push( obj );
}
console.log( outputObj );
for ( var key in outputObj )
{
result.push( mergeArray( outputObj[ key ] ) );
}
return result;
}
console.log( collateArray( array ) );

Use an temp Object as a map that stores key => item can make the time complexity to O(n):
var arr = [
{
"id_0":356,
"name":"India",
"key1":150
},
{
"id_0":356,
"name":"India",
"key2":200
},
{
"id_0":748,
"name":"Swaziland",
"key1":140
},
{
"id_0":748,
"name":"Swaziland",
"key2":180
}
];
// items: the array to be merged to unique.
// attrName: the attribute's name that is for distinguish,
// isOverwrite:decides whether the value will be overwrite by later ones or not. Default to false.
function getUnique(items, attrName, isOverwrite) {
// Map to keep reference to objects by its id.
var store = {};
// The array for output result.
var result = [];
isOverwrite = !!isOverwrite;
items.forEach(function(item) {
var id = item[attrName];
var key;
// Try to fetch item by id from store.
var target = store[id];
// If target item exist in store, its dulplicated, we need to merge it.
if (typeof target !== 'undefined') {
// If it's presented, we need to merge it into existing one.
for (key in item) {
if (!item.hasOwnProperty(key)) {
continue;
}
// If isOverwrite is true, always use the newest value, otherwise,
// we only apply values that are not exist in target yet.
if (isOverwrite || typeof target[key] === 'undefined') {
target[key] = item[key];
}
}
} else {
// If its not in store yet, put it a clone into result, and to map for
// later reference.
var clone = {};
for (key in item) {
if (item.hasOwnProperty(key)) {
clone[key] = item[key];
}
}
store[id] = clone;
// Also put it into the result array.
result.push(clone);
}
});
return result;
}
console.log(getUnique(arr, 'id_0'));

Split array of objects into new array or objects based on age value

Split array of objects into new array or objects based on age value in Javascript
var items = [
{name:"Foo", age:16, color:"w"},
{name:"Bar", age:18, color:"b"},
{name:"foo", age:16, color:"w"},
{name:"bar", age:18, color:"w"},
{name:"foobar", age:18, color:"b"},
{name:"barfoo", age:20, color:"w"}
];
How can I return a list like:
var items = [
{age:16,name:"Foo"|"foo",gender:"w"|"w"},
{age:18,name:"Bar"|"bar"|"foobar",gender:"b"|"w"|"b"},
{age:20,name:"barfoo",gender:"w"}
];
I have worked but i got output with 'undefined' in name. Below is my code.
var data = [{age: 21,name: "Walter",color: "black"},{age: 25,name: "sentinel",color: "black"
},{age: 21,name: "Micah",color: "purple"},{age: 25,name: "mike",color: "black"},{age: 21,name: "Danny",color: "white"},{age: 25,name: "mike",color: "black"}];
var obj=data;
var arrayobj = obj.length;
var i, row, arr = obj, ss = {};
for (i = 0; i < arr.length; i++) {
row = arr[i];
ss[row.age] = ss[row.age] || {count: 0};
if (ss[row.age][row.age] === undefined) {
ss[row.age][row.name] = row.name;
ss[row.age]['name']+=row.name+'|';
ss[row.age]['color']+=row.color+'|';
ss[row.age]['count'] += 1;
}
}
console.table(ss);

I'm assuming you want to group the items by their age. Here is one way:
(fiddle)
items.reduce(function(buckets,item){
if(!buckets[item.age]) buckets[item.age] = [];
buckets[item.age].push(item);
return buckets;
},{});
Let's explain:
For each item, if we don't already have a 'bucket' for it, create a new empty one
Add it to the bucket
return the new updated bucket list.
The method returns an object with 3 properties: 16,18 and 20, each containing the objects with that age.

This will work. The output is in different format than one provided by exebook .
Please check and confirm. Here's a fiddle....
** UX Manager
var buckets = [];
for (var item in items) {
var currentAge = items[item].age;
if(!buckets[currentAge]) {
buckets[currentAge] = [];
for (var i in items) {
if (currentAge === items[i].age) {
buckets[currentAge].push(items[i]);
}
}
}
}

var items = [
{name:"Foo", age:16, color:"w"},
{name:"Bar", age:18, color:"b"},
{name:"foo", age:16, color:"w"},
{name:"bar", age:18, color:"w"},
{name:"foobar", age:18, color:"b"},
{name:"barfoo", age:20, color:"w"}
];
var result = [] // THIS IS THE RESULTING ARRAY THAT YOU WANT
function find(age) {
for (var i = 0; i < result.length; i++)
if (result[i].age == age) return i
return -1
}
function append(i, obj) {
result[i].name.push(obj.name)
result[i].color.push(obj.color)
}
for (var i = 0; i < items.length; i++) {
var x = find(items[i].age)
if (x < 0) result.push({ age: items[i].age, name: [items[i].name], color : [items[i].color]})
else append(x, items[i])
}
console.log(result) // PRINT THE RESULT, alternatively you can use alert(result)
The output
[ { age: 16, name: [ 'Foo', 'foo' ], color: [ 'w', 'w' ] },
{ age: 18, name: [ 'Bar', 'bar', 'foobar' ], color: [ 'b', 'w', 'b' ] },
{ age: 20, name: [ 'barfoo' ], color: [ 'w' ] } ]