I am trying to find duplicate objects in a list of objects and add new parameters to the duplicate one.
Below snipped code is what I implemented so far. The problem is that it adds desired parameters to every object in the list.
const list = [{
id: 1,
name: 'test1'
},
{
id: 2,
name: 'test2'
},
{
id: 3,
name: 'test3'
},
{
id: 2,
name: 'test2'
}
];
const newList = list.reduce(
(unique, item) => (unique.includes(item) ? unique : [...unique, {
...item,
duplicated: true,
name: `${item.name}_${item.id}`
}]), []
);
console.log(newList);
Since there are two duplicate objects by id, the duplicated one should have duplicated and new name parameters. What part is wrong in my implementation?
By using findIndex method:
const list = [{
id: 1,
name: 'test1'
},
{
id: 2,
name: 'test2'
},
{
id: 3,
name: 'test3'
},
{
id: 2,
name: 'test2'
}
];
const newList = list.reduce(
(unique, item) => (unique.findIndex(x => x.id === item.id) > -1 ? [...unique, {
...item,
duplicated: true,
name: `${item.name}_${item.id}`
}] : [...unique, item]), []);
console.log(newList);
It can be written simply:
const
list = [
{ id: 1, name: 'test1' },
{ id: 2, name: 'test2' },
{ id: 3, name: 'test3' },
{ id: 2, name: 'test2' }
],
uniqueList = list.reduce((arr, { id, name }) =>
arr.concat({
id,
name,
...arr.some(item => id === item.id) && { duplicate: true, name: `${name}_${id}` }
}), []);
console.log(uniqueList);
The problem was that when you called includes you were actually looking for an object whose pointer exists in the array.
In order to find an object which has property are the same as a requested property, you have no choice but to use functions such as some or every that is different from includes - you can send them a callback and not just an object.
Related
So I am making a filter functionality for React, so I have an array of objects, and based on another array that contains values to filter the array, I need to get the filtered values.
code: the array of objects to apply the filter to:
const citiesData = [
{
id: 1,
name: 'amritsar',
popu: '1200'
},
{
id: 2,
name: 'jalandhar',
popu: '1300'
},
{
id: 3,
name: 'phagwara',
popu: '1200'
},
{
id: 4,
name: 'ludhiana',
popu: '1400'
},
{
id: 5,
name: 'mumbai',
popu: '2000'
},
{
id: 6,
name: 'banglore',
popu: '2000'
},
{
id: 7,
name: 'ohter city 1',
popu: '1500'
},
{
id: 8,
name: 'ohter city 2',
popu: '1500'
},
{
id: 9,
name: 'anohter city 1',
popu: '2200'
},
{
id: 10,
name: 'anohter city 2',
popu: '2200'
},
]
code: filters array based on what I need to apply the conditions:
const filterCity = [
{
filterType: 'name',
filterValue: 'amritsar'
},
{
filterType: 'popu',
filterValue: '1200'
}
]
solutions I've tried:-
code: solution 1:
const filteredList = citiesData.filter(item => {
return filterCity.filter(fItem => item[fItem.filterType] === fItem.filterValue).length
})
code: solution 2:
const filteredList = citiesData.filter(item => {
return filterCity.reduce((acc, val) => {
if(item[val.filterType] === val.filterValue) {
acc = true
}
return acc;
}, false)
})
code: result I'm getting:
[
{ id: 1, name: 'amritsar', popu: '1200' },
{ id: 3, name: 'phagwara', popu: '1200' }
]
it's giving me two objects because according to the filters array I'm searching for the name and popu fields. but the expected result should be:
[ { id: 1, name: 'amritsar', popu: '1200' } ]
because the name and popu is similar in that but in the second object the name is not the same.
I want the code to check all the conditions and then give me the result. right now it's working on the individual filter and individual array item.
so can anyone help me on this!!
so, it should be an AND filter (combining all conditions)?
res = citiesData.filter(d =>
filterCity.every(f => d[f.filterType] === f.filterValue))
for the OR filter (any condition), replace every with some.
I am trying to swap out all the values of an array of objects in state with a whole new array of objects. However, nothing seems to be working. I've tried the following:
const list1 = [
{ id: 1, name: 'item1' },
{ id: 2, name: 'item1' },
{ id: 3, name: 'item1' },
{ id: 4, name: 'item1' },
]
const list2 = [
{ id: 1, name: 'newItem1' },
{ id: 2, name: 'newItem2' },
{ id: 3, name: 'newItem3' },
{ id: 4, name: 'newItem4' },
]
class FindTab extends Component {
state = {
status: 'loading',
location: null,
view: this.props.view,
map: this.props.map,
locationValues: list1,
}
}
this.setState(prevState => ({
locationValues: [ ...prevState.locationValues, list2 ],
}))
or just simpler:
this.setState(locationValues: list2)
Neither seem to work. Is there any guidance as to how one should replace an array of objects with another array for a state property?
You could spread the array in a new one like:
const locationValues = [ ...state.locationValues, ...list2 ]
this.setState({ locationValues })
This question already has answers here:
Create array of unique objects by property
(17 answers)
Closed 3 years ago.
I have an object that looks like this:
const posts = [
{ id: 0, user: { id: 5564, name: 'john'} },
{ id: 1, user: { id: 5564, name: 'john'} },
{ id: 2, user: { id: 5560, name: 'jane'} }
]
I need an array of the unique user hashes like this:
[
{ id: 5564, name: 'john'},
{ id: 5560, name: 'jane'}
]
I'm able to retrieve all the users attributes from the posts array by doing:
const postUsers = posts.map(post => post.user)
which returns:
[
{ id: 5564, name: 'john'},
{ id: 5564, name: 'john'},
{ id: 5560, name: 'jane'}
]
where user john is listed twice
I've been able to get my desired result by doing:
const unique = {};
const uniqueUsers = [];
for(var i in postUsers){
if(typeof(unique[postUsers[i].id]) == "undefined"){
uniqueUsers.push(postUsers[i]);
}
unique[postUsers[i].id] = 0;
};
uniqueUsers
but there must be a cleaner way.
I've also been able to return the unique ids of all users by doing:
var ids = posts.map(post => post.user.id)
var uniqueIds = Array.from(new Set(ids)).sort();
which returns
[5564, 5560]
not sure if that helps. this article helped me a little https://medium.com/tomincode/removing-array-duplicates-in-es6-551721c7e53f
You could take a Map and get only the unique users.
const
posts = [{ id: 0, user: { id: 5564, name: 'john'} }, { id: 1, user: { id: 5564, name: 'john'} }, { id: 2, user: { id: 5560, name: 'jane'} }],
unique = Array.from(posts.reduce((m, { user }) => m.set(user.id, user), new Map).values());
console.log(unique);
If you don't mind using lodash you can do something like
const users = _map.(posts, 'user') // To get the list of users
_.uniqBy(users, 'id') // to get the uniq ones
Put the objects directly in uniqueUsers, then use Object.values() at the end to convert the object to an array.
const posts = [
{ id: 0, user: { id: 5564, name: 'john'} },
{ id: 1, user: { id: 5564, name: 'john'} },
{ id: 2, user: { id: 5560, name: 'jane'} }
];
let uniqueUsers = {};
posts.forEach(({user}) => uniqueUsers[user.id] = user);
uniqueUsers = Object.values(uniqueUsers);
console.log(uniqueUsers);
Use reduce to reduce the array by checking if the value is already in the array. If it is already in the array, return the current state of the array, otherwise add the item to the array.
const posts = [
{ id: 0, user: { id: 5564, name: 'john'} },
{ id: 1, user: { id: 5564, name: 'john'} },
{ id: 2, user: { id: 5560, name: 'jane'} }
]
const r = posts.map(i => i.user).reduce((acc, itm) => {
return !acc.find(i => i.id == itm.id) && acc.concat(itm) || acc
}, [])
console.log(r)
I have one user array like:
var users = [{
id: 1,
name: 'ABC',
isDisplay: true
}, {
id: 2,
name: 'XYZ',
isDisplay: true
}, {
id: 3,
name: 'JKL',
isDisplay: true
}];
And another array selectedUsers which contains some object from above array like:
var selectedUsers = [{
id: 1,
name: 'ABC'
},
{
id: 3,
name: 'JKL'
}];
Not with lodash, i want to indentify which object are present in second array with matching its ID.
_.each(users, (_u) => {
if(selectedUsers.includes(_u)) {
_u.isDisplay = false;
} else {
_u.isDisplay = true;
}
});
I have tried to match whole object with includes but it dint work, because i am using angularjs, so angular put some $$hashkey with object, so it will not match, Is there any other way to do this.
var users = [{
id: 1,
name: 'ABC',
isDisplay: true
}, {
id: 2,
name: 'XYZ',
isDisplay: true
}, {
id: 3,
name: 'JKL',
isDisplay: true
}];
var selectedUsers = [{
id: 1,
name: 'ABC'
},
{
id: 3,
name: 'JKL'
}];
var intersection = _.intersectionBy(users, selectedUsers, 'id');
console.log(intersection);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.13.1/lodash.js"></script>
Create a Set of selected ids (selectedUsersIds). Iterate the users array with Array#forEach, assign the value of isDisplay by checking if the id exists in the selectedUsersIds set:
const users = [{"id":1,"name":"ABC","isDisplay":true},{"id":2,"name":"XYZ","isDisplay":true},{"id":3,"name":"JKL","isDisplay":true}];
const selectedUsers = [{"id":1,"name":"ABC"},{"id":3,"name":"JKL"}];
const selectedUsersIds = new Set(selectedUsers.map(({ id }) => id));
users.forEach((u) => u.isDisplay = selectedUsersIds.has(u.id));
console.log(users);
I have an array of objects:
[
{ id: 1, name: "Bob" },
{ id: 1, name: "Donald" },
{ id: 2, name: "Daryl" }
]
I'd like to strip out objects with duplicate Ids, leaving an array that would look like this:
[
{ id: 1, name: "Bob" },
{ id: 2, name: "Daryl" }
]
I don't care which objects are left, as long as each ID is unique. Anything in Underscore, maybe, that would do this?
Edit: This is not the same as the duplicate listed below; I'm not trying to filter duplicate OBJECTS, but objects that contain identical IDs. I've done this using Underscore - I'll post the answer shortly.
You can use reduce and some to good effect here:
var out = arr.reduce(function (p, c) {
// if the next object's id is not found in the output array
// push the object into the output array
if (!p.some(function (el) { return el.id === c.id; })) p.push(c);
return p;
}, []);
DEMO
the es6 way
function removeDuplicates(myArr, prop) {
return myArr.filter((obj, pos, arr) => {
return arr.map(mapObj => mapObj[prop]).indexOf(obj[prop]) === pos
})
}
Test it
let a =[
{ id: 1, name: "Bob" },
{ id: 1, name: "Donald" },
{ id: 2, name: "Daryl" }
]
console.log( removeDuplicates( a, 'id' ) )
//output [
{ id: 1, name: "Bob" },
{ id: 2, name: "Daryl" }
]
If you use underscore, you can use the _uniq method
var data = [
{ id: 1, name: "Bob" },
{ id: 1, name: "Donald" },
{ id: 2, name: "Daryl" }
]
_.uniq(data, function(d){ return d.ID });
Produces a duplicate-free version of the array, using === to test object equality. In particular only the first occurence of each value is kept. If you know in advance that the array is sorted, passing true for isSorted will run a much faster algorithm. If you want to compute unique items based on a transformation, pass an iteratee function.
Source: http://underscorejs.org/#uniq
Can use es6 Map collection mix with reduce
const items = [
{ id: 1, name: "Bob" },
{ id: 1, name: "Donald" },
{ id: 2, name: "Daryl" }
]
const uniqItems = [...items.reduce((itemsMap, item) =>
itemsMap.has(item.id) ? itemsMap : itemsMap.set(item.id, item)
, new Map()).values()]
console.log(uniqItems);
Using findIndex should be the simplest solution.
array.filter((elem, index, arr) => arr.findIndex(e => e.id === elem.id) === index)
You can simply filter the array, but you'll need an index of existing IDs that you've already used...
var ids = [];
var ar = [
{ id: 1, name: "Bob" },
{ id: 1, name: "Donald" },
{ id: 2, name: "Daryl" }
];
ar = ar.filter(function(o) {
if (ids.indexOf(o.id) !== -1) return false;
ids.push(o.id);
return true;
});
console.log(ar);
Here's some documentation on filter()...
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/filter