I'm wondering, I have the following data structure:
data = [
{
name: 'Alpha',
},
{
name: 'Alfa',
},
{
name: 'Bravo',
},
{
name: 'Brafo',
},
{
name: 'Charlie',
},
{
name: 'Charly',
},
...
{
name: 'Zulu',
},
{
name: 'Zulo',
},
]
I'm expecting there to be at least one, usually more, key for each letter of the alphabet. However, if there isn't a single data.name I would still like in the below data structure to have an empty domains array [].
I was wondering, how could this be manipulated into the following data structure:
data = {
a: {
domains: [
{
name: 'Alpha',
},
{
name: 'Alfa',
},
],
},
b: {
domains: [
...
]
},
...
z: {
domains: [
...
]
},
};
I have used a few methods, which involved a pre-constructed "alphbetised" key = object array, then filtered each on the first letter of the data.name value...but I was wondering if there was a standard and performant method to acheive this?
Using reduce()
const data = [{name:"Alpha"},{name:"Alfa"},{name:"Bravo"},{name:"Brafo"},{name:"Charlie"},{name:"Charly"},{name:"Zulu"},{name:"Zulo"}]
const res = data.reduce((a, v) => {
// prepare key
let key = v.name.substring(0,1).toLowerCase()
// check key in accumulator
if (!a[key]) {
// assign domain object
a[key] = {domains: []}
}
// push domain array
a[key].domains.push(v)
return a
}, {})
console.log(res)
Here is what you want:
data = [
{
name: 'Alpha',
},
{
name: 'Alfa',
},
{
name: 'Bravo',
},
{
name: 'Brafo',
},
{
name: 'Charlie',
},
{
name: 'Charly',
},
{
name: 'Zulu',
},
{
name: 'Zulo',
},
];
console.log(data.reduce((a, c) => {
const firstLetter = c.name[0].toLowerCase();
if (a[firstLetter]) {
a[firstLetter].domains.push(c);
} else {
a[firstLetter] = { domains: [c] };
}
return a;
}, {}));
Related
I am trying to remove all the _er and _bx from the array, how can I do it? The way I tried doesn't seem to work. I'd like to see a solution where it removes all after _, and aswell only the letter that I put in for e.g remove all _ with er after.
const nullValue = {
collection: [{
name: "test_er"
},
{
name: "test_bx"
},
{
name: "fred"
},
{
name: "test_er"
}
]
};
const newArr = []
for (let [key, item] of nullValue.collection.entries()) {
item.name.replace(/_er/g, '')
newArr.push(item)
}
console.log(newArr)
Is this what you're looking for?
const nullValue = {
collection: [
{
name: 'test_er',
},
{
name: 'test_bx',
},
{
name: 'fred',
},
{
name: 'test_er',
},
],
};
nullValue.collection = [
...nullValue.collection.map(item => ({
name: item.name.replace(/_.*$/, ''),
})),
];
console.log(nullValue);
You can also use .split('_')[0] with the map method similar to Dmitry's answer... This gives you the first string of the split array, split at the underscore...
const nullValue = {
collection: [{
name: "test_er"
},
{
name: "test_bx"
},
{
name: "fred"
},
{
name: "test_er"
}
]
};
nullValue.collection = [ ...nullValue.collection.map( names => ({ name: names.name.split('_')[0], })),]
console.log(nullValue)
If you want to keep the original array of objects...
const nullValue = {
collection: [{
name: "test_er"
},
{
name: "test_bx"
},
{
name: "fred"
},
{
name: "test_er"
}
]
};
const newArr = { collection :
[ ...nullValue.collection.map( names =>
({ name: names.name.split('_')[0], })),
]}
console.log('newArr = ', newArr)
console.log('nullValue = ', nullValue)
You were VERY close with your original code, but the mistake was that String.replace() does not operate in-place, but rather returns its result. I've modified your code and added a comment below:
const nullValue = {
collection: [{
name: "test_er"
},
{
name: "test_bx"
},
{
name: "fred"
},
{
name: "test_er"
}
]
};
const newArr = []
for (let [key, item] of nullValue.collection.entries()) {
// My change is here
newArr.push( item.name.replace(/_er/g, '') )
}
console.log(newArr)
const nullValue = {
collection: [
{
name: "test_er"
},
{
name: "test_bx"
},
{
name: "fred"
},
{
name: "test_er"
}
]
};
nullValue.collection = nullValue.collection.map(i => i.name.replace(/_.*$/, ''))
console.log(nullValue)
This is preferable to .map() since you don't need a new array. You just want to change the strings:
const nullValue = {
collection: [
{ name: "test_er" },
{ name: "test_bx" },
{ name: "fred" },
{ name: "test_er" }
]
};
nullValue.collection.forEach(i => i.name = i.name.replace(/_.*$/, ''));
console.log(nullValue.collection);
I wonder how I can group this array based on the prefix text in name key (split the name key at the : colon) using Lodash.
const tags = [
{ name: 'Animals: Frogs', id: 1 },
{ name: 'Animals: Lions', id: 2 },
{ name: 'Birds: Crows', id: 3 }
];
to
const tags = [{
animals: [
{ name: 'Frogs', id: 1 },
{ name: 'Lions', id: 2 },
],
birds: [
{ name: 'Crows', id: 3}
]
}];
Does Lodash have any functions to handle this, or is a custom function/regex needed?
If the pure JS suffices, it can be done this way (the result is an object here, not an array, but this can be changed if needed):
const tags = [
{ name: 'Animals: Frogs', id: 1 },
{ name: 'Animals: Lions', id: 2 },
{ name: 'Birds: Crows', id: 3 }
];
const tags2 = tags.reduce(
(acc, { name, id }) => {
let [group, type] = name.split(': ');
group = group.toLowerCase();
acc[group] ??= [];
acc[group].push({ name: type, id });
return acc;
},
{},
);
console.log(tags2);
Here is what I have
[
{
typeProgramId: {
name: 'type1',
},
title: 'test1',
},
{
typeProgramId: {
name: 'type1',
},
subTypeProgramId: [{
name: 'sub1',
}],
title: 'test2',
},
{
typeProgramId: {
name: 'type2',
},
title: 'test3',
},
{
typeProgramId: {
name: 'type2',
},
subTypeProgramId: {
name: 'sub2',
},
title: 'test4',
}
]
First I want to group typeProgramId if the title have the same typeProgramId I want to push title into array by each typeProgramId but If the data have typeProgramId and subTypeProgram Id I want to group subtypeProgramId in typeProgramId too. if not empty subtypeProgramId I want to push it in array title inside subtypeProgram Id. I try to use lodash groupBy and many way but it still did not work.
Here is what I want
{
typeProgramId: [{
name: 'type1',
title: [
'test1',
],
subTypeProgramId: {
name: sub1,
title: [
'test2'
]
}
}, {
name: 'type2',
title: [
'test3',
],
subTypeProgramId: [{
name: sub1,
title: [
'test4'
]
}
}]
}
what I do now
let result = _.groupBy(getProgram, function(data) {
return data.typeProgramId
})
result = _.map(result, function(group, data) {
// I think in here I must groupBy subTypeProgramId again
// the data return all string not object after group
return {
typeProgramId: data,
titile: group,
}
})
Please check the below code. I have used reduce function of Array. It produces the expected result.
function updateMem(mem, prgIndex, val){
if(prgIndex < 0) {
mem.typeProgramId.push({});
prgIndex = mem.typeProgramId.length - 1;
}
mem.typeProgramId[prgIndex].name = val.typeProgramId.name;
if(val.subTypeProgramId){
mem.typeProgramId[prgIndex].subTypeProgramId = Object.assign({}, mem.typeProgramId[prgIndex].subTypeProgramId || {}, {"name" : val.subTypeProgramId.name, "title": []});
mem.typeProgramId[prgIndex].subTypeProgramId.title.push(val.title);
} else {
mem.typeProgramId[prgIndex].title = (mem.typeProgramId[prgIndex].title ? mem.typeProgramId[prgIndex].title : []);
mem.typeProgramId[prgIndex].title.push(val.title);
}
};
arr.reduce((mem, val) => {
var prgIndex = mem.typeProgramId.findIndex((p) => p.name === val.typeProgramId.name);
updateMem(mem, prgIndex, val);
return mem;
}, {typeProgramId: []});
I have the following array of deeply nested objects:
const data = [
{
name: "foo",
children:[
{
count: 1,
name: "A"
},
{
count: 2,
name: "B"
}
]
},
{
name: "bar",
children: [
{
count: 3,
name: "C",
children: [
{
count: 4,
name: "D"
}
]
}
]
}
]
The way I'd like to transform this would be such as:
const expectedStructure = [
{
count: 1,
name: "A",
label: "foo = A"
},
{
count: 2,
name: "B",
label: "foo = B"
},
{
count: 3,
name: "C",
label: "bar = C"
},
{
count: 4,
name: "D",
label: "bar = D"
}
]
I created recursive function that transforms nested array into array of flat objects.
Here's my code:
function getChildren(array, result=[]) {
array.forEach(({children, ...rest}) => {
result.push(rest);
if(children) {
getChildren(children, result);
}
});
return result;
}
And here's output I get:
[ { name: 'foo' },
{ count: 1, name: 'A' },
{ count: 2, name: 'B' },
{ name: 'bar' },
{ count: 3, name: 'C' },
{ count: 4, name: 'D' } ]
The problem is that I need to add label field to every object in my output array, and I can't find a solution without iterating multiple times through the final array to make desired transformation. How to properly insert label field without hugely augmenting complexity of the function?
Check each iteration whether the current item is a "parent" item, and reassign label if it is.
const data = [{name:"foo",children:[{count:1,name:"A"},{count:2,name:"B"}]},{name:"bar",children:[{count:3,name:"C",children:[{count:4,name:"D"}]}]}];
function getChildren(array, result = [], label = "") {
array.forEach(({ children, name, count }) => {
if (!label || name[1]) {
label = `${name} = `;
}
if (count) {
result.push({ count, name, label: label + name });
}
if (children) {
getChildren(children, result, label);
}
});
return result;
}
const res = getChildren(data);
console.log(res);
You can use a different function for the nested levels, so you can pass the top-level name properties down through all those recursion levels.
function getTopChildren(array, result = []) {
array.forEach(({
name,
children
}) => {
if (children) {
getChildren(children, name, result);
}
});
return result;
}
function getChildren(array, name, result) {
array.forEach(({
children,
...rest
}) => {
rest.label = `${name} = ${rest.name}`;
result.push(rest);
if (children) {
getChildren(children, name, result);
}
});
}
const data = [{
name: "foo",
children: [{
count: 1,
name: "A"
},
{
count: 2,
name: "B"
}
]
},
{
name: "bar",
children: [{
count: 3,
name: "C",
children: [{
count: 4,
name: "D"
}]
}]
}
]
console.log(getTopChildren(data));
You can also do this recursively with flatMap based on whether or not a parent has been passed into the recursive call :
const data = [{
name: "foo",
children: [{
count: 1,
name: "A"
},
{
count: 2,
name: "B"
}
]
},
{
name: "bar",
children: [{
count: 3,
name: "C",
children: [{
count: 4,
name: "D"
}]
}]
}
];
function flatten(arr, parent = null) {
return parent
? arr.flatMap(({name, count, children}) => [
{name, count, label: `${parent} = ${name}`},
...flatten(children || [], parent)
])
: arr.flatMap(({name, children}) => flatten(children || [], name));
}
console.log(flatten(data));
Sometimes it's a little easier to reason about the code and write it clearly using generators. You can yield* from the recursive calls:
const data = [{name: "foo",children:[{count: 1,name: "A"},{ count: 2,name: "B"}]},{name: "bar",children: [{count: 3,name: "C",children: [{count: 4,name: "D"}]}]}]
function* flat(input, n){
if (!input) return
if (Array.isArray(input)) {
for (let item of input)
yield* flat(item, n)
}
let _name = n || input.name
if ('count' in input) {
yield { count:input.count, name:input.name, label:`${_name} = ${input.name}`}
}
yield* flat(input.children, _name)
}
let g = [...flat(data)]
console.log(g)
The function returns a generator, so you need to spread it into a list [...flat(data)] if you want a list or iterate over it if you don't need to store the list.
Suppose there are two objects.
const a = [
{ id: '1-1-1', name: 'a111' },
{ id: '1-1-2', name: 'a112' },
{ id: '1-2-1', name: 'a121' },
{ id: '1-2-2', name: 'a122' },
{ id: '2-1-1', name: 'a211' },
{ id: '2-1-2', name: 'a212' }
]
const b = ['1-1', '1-2', '2-1']
and the result
{
'1-1':[
{ id: '1-1-1', name: 'a111' },
{ id: '1-1-2', name: 'a112' },
],
'1-2':[
{ id: '1-2-1', name: 'a121' },
{ id: '1-2-2', name: 'a122' },
],
'2-1':[
{ id: '2-1-1', name: 'a211' },
{ id: '2-1-2', name: 'a212' },
]
}
Basically, I want to group the data.
I use includes to check if the item from b to match the id from a. Then construct the new array.
This is my attempt(fiddle):
return b.map(item => a.map(jtem => {
if(jtem.id.includes(item)){
return {
[item]: jtem
}
}
}))
For somehow, it doesn't work.
and, is there a clever way to avoid the nested for loop or map function?
You can do that in following steps:
Apply reduce() on the array b
During each iteration use filter() on the the array a
Get all the items from a which starts with item of b using String.prototype.startsWith()
At last set it as property of the ac and return ac
const a = [
{ id: '1-1-1', name: 'a111' },
{ id: '1-1-2', name: 'a112' },
{ id: '1-2-1', name: 'a121' },
{ id: '1-2-2', name: 'a122' },
{ id: '2-1-1', name: 'a211' },
{ id: '2-1-2', name: 'a212' }
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) => {
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
},{})
console.log(res)
As suggested by #Falco is the comments that It would be better to scan over the a once as its large. So here is that version.Actually its better regarding performance
const a = [
{ id: '1-1-1', name: 'a111' },
{ id: '1-1-2', name: 'a112' },
{ id: '1-2-1', name: 'a121' },
{ id: '1-2-2', name: 'a122' },
{ id: '2-1-1', name: 'a211' },
{ id: '2-1-2', name: 'a212' }
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) => {
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
},{})
console.log(res)
Note: startsWith is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith){
String.prototype.startsWith = function(str){
return this.indexOf(str) === 0
}
}