I have a data object as below:
[{"Positive":"14.71","Neutral":"50.0","Negative":"35.29"}]
I want to change this to the below specified format:
[{"type":"Positive","value":14.71},{"type":"Neutral","value":50.0},{"type":"Negative","value":35.29}]
Use Object.keys and Array#map methods.
var data = [{
"Positive": "14.71",
"Neutral": "50.0",
"Negative": "35.29"
}];
var res = Object.keys(data[0]) // get all object property names
// iterate over property names array
.map(function(k) {
// generate array element using property value
return {
type: k,
// cast data value to number using plus-sign prefix(as per requirement)
value: +data[0][k]
}
})
console.log(res);
I solve this using a generic pairs function which will be useful for you when trying to map, reduce, or filter objects in JavaScript
let input = [{"Positive":"14.71","Neutral":"50.0","Negative":"35.29"}];
let pairs = o =>
Object.keys(o).reduce((acc,k) => [...acc, [k, o[k]]], []);
let output = pairs(input[0]).map(([type,value]) =>
({type, value: Number(value)}));
console.log(output);
Alternatively, pairs can be implemented as a generator which will produce an overall more readable result
let input = [{"Positive":"14.71","Neutral":"50.0","Negative":"35.29"}];
function* pairs(o) {
for (let k of Object.keys(o))
yield [k, o[k]];
}
let output = Array.from(pairs(input[0]), ([type, value]) => {
return {type, value: Number(value)};
});
console.log(output);
Array.from provides a convenient way to collect values from an iterable value (and optionally map over them too), but you don't have to use it if you don't want to. Before you become familiar with it, you could just as easily use a for-of loop to collect the key/value pairs into your output object.
let input = [{"Positive":"14.71","Neutral":"50.0","Negative":"35.29"}];
function* pairs(o) {
for (let k of Object.keys(o))
yield [k, o[k]];
}
let output = [];
for (let [type, value] of pairs(input[0]))
output.push({type, value: Number(value)});
console.log(output);
Related
Suppose I have an array of object:
const apple = [{"bookName" :'Harry Pottar',part:"1"},{"bookName" :'Harry Pottar',part:"2"},
{"bookName": 'LOTR',part:"1"},{"bookName": 'LOTR',part:"2"},{"bookName": 'LOTR',part:"3"}]
I want to get count of all common values along with the value name as :
Expected O/P : [{"Harry Pottar":2},{"LOTR":3"}]
For this I tried as:
const id = "Harry Pottar";
const count = array.reduce((acc, cur) => cur.bookName === id ? ++acc : acc, 0);
As this gives the count, by this I can get count for each bookName. But how can I achieve my expected O/P scenario.
If anyone needs any further information please do let me know.
Good to see you know about .reduce! You’re pretty close, just need to save the result to a hashmap (plain object in JS).
const array = [{"bookName" :'Harry Pottar',part:"1"},{"bookName" :'Harry Pottar',part:"2"},{"bookName": 'LOTR',part:"1"},{"bookName": 'LOTR',part:"2"},{"bookName": 'LOTR',part:"3"}]
const result = array.reduce((acc, item) => {
const key = item.bookName
if (!acc.hasOwnProperty(key)) {
acc[key] = 0
}
acc[key] += 1
return acc
}, {})
// not sure why you want the result to be multiple objects. But here you go:
const output = Object.entries(result).map(([key, value])=> ({ [key]: value }))
Create a map from your data keyed by the book names, where the corresponding values are the objects you want in the output, with the count set to zero (you can use the computed property name syntax for the object's dynamic property). Then iterate the data again to increment the counters. Finally extract the values from the map into an array:
const apple = [{"bookName" :'Harry Pottar',part:"1"},{"bookName" :'Harry Pottar',part:"2"},
{"bookName": 'LOTR',part:"1"},{"bookName": 'LOTR',part:"2"},{"bookName": 'LOTR',part:"3"}];
let map = new Map(apple.map(({bookName}) => [bookName, { [bookName]: 0 }]));
for (let {bookName} of apple) map.get(bookName)[bookName]++;
let result = Array.from(map.values());
console.log(result);
You were pretty close. You don't necessarily need to have those objects in an array though. Just have an object with the booknames as the property keys. It would make it easier to manage.
If you then want to create an array of objects from that data you can use map over the Object.entries of that object.
const apple = [{"bookName" :'Harry Pottar',part:"1"},{"bookName" :'Harry Pottar',part:"2"},{"bookName": 'LOTR',part:"1"},{"bookName": 'LOTR',part:"2"},{"bookName": 'LOTR',part:"3"}];
const out = apple.reduce((acc, { bookName }) => {
// If the property doesn't exist, create it
// and set it to zero, otherwise increment the value
// of the existing property
acc[bookName] = (acc[bookName] || 0) + 1;
return acc;
}, {});
console.log(out);
const result = Object.entries(out).map(([ key, value ]) => {
return { [key]: value };
});
console.log(result);
so I want to find unique values from an array.
so for example I have this array:
const mainArr = ['shape-10983', 'size-2364', 'size-7800', 'size-4602', 'shape-11073', 'size-15027', 'size-15030', 'size-15033', 'height-3399', 'height-5884']
so I want to find the first matching value for each unique item.
for example, in the array, I have two strings with the shape prefix, six items with the size prefix, and two items with the height prefix.
so I want to output to be something like
const requiredVal = ["shape-10983", "size-2364", "height-3399"]
I want only the first value from any set of different values.
the simplest solution will be to iterate on the list and storing what you got in a dictionary
function removeSimilars(input) {
let values = {};
for (let value of input) {//iterate on the array
let key = value.splitOnLast('-')[0];//get the prefix
if (!(key in values))//if we haven't encounter the prefix yet
values[key] = value;//store that the first encounter with the prefix is with 'value'
}
return Object.values(values);//return all the values of the map 'values'
}
a shorter version will be this:
function removeSimilars(input) {
let values = {};
for (let value of input)
values[value.splitOnLast('-')[0]] ??= value;
return Object.values(values);
}
You could split the string and get the type and use it aks key for an object along with the original string as value. At result take only the values from the object.
const
data = ['shape-10983', 'size-2364', 'size-7800', 'size-4602', 'shape-11073', 'size-15027', 'size-15030', 'size-15033', 'height-3399', 'height-5884'],
result = Object.values(data.reduce((r, s) => {
const [type] = s.split('-', 1);
r[type] ??= s;
return r;
}, {}));
console.log(result);
If, as you mentioned in the comments, you have the list of prefixes already available, then all you have to do is iterate over those, to find each first element that starts with that prefix in your full list of possible values:
const prefixes = ['shape', 'size', 'height'];
const list = ['shape-10983', 'size-2364', 'size-7800', 'size-4602', 'shape-11073', 'size-15027', 'size-15030', 'size-15033', 'height-3399', 'height-5884']
function reduceTheOptions(list = [], prefixes = [], uniques = []) {
prefixes.forEach(prefix =>
uniques.push(
list.find(e => e.startsWith(prefix))
)
);
return uniques;
}
console.log(reduceTheOptions(list, prefixes));
Try this:
function getRandomSet(arr, ...prefix)
{
// the final values are load into the array result variable
result = [];
const randomItem = (array) => array[Math.floor(Math.random() * array.length)];
prefix.forEach((pre) => {
result.push(randomItem(arr.filter((par) => String(par).startsWith(pre))));
});
return result;
}
const mainArr = ['shape-10983', 'size-2364', 'size-7800', 'size-4602', 'shape-11073', 'size-15027', 'size-15030', 'size-15033', 'height-3399', 'height-5884'];
console.log("Random values: ", getRandomSet(mainArr, "shape", "size", "height"));
I modified the #ofek 's answer a bit. cuz for some reason the ??= is not working in react project.
function removeSimilars(input) {
let values = {};
for (let value of input)
if (!values[value.split("-")[0]]) {
values[value.split("-")[0]] = value;
}
return Object.values(values);
}
create a new array and loop over the first array and check the existing of element before in each iteration if not push it to the new array
How do I convert ["one","two","three"] into {one:"one", two:"two", three:"three"}
import stringArray from './a.js';
class b {
hashmap = stringArray// convert this into Object here inline.
}
Before you jump I know of for how to achieve this in say constructor() with tricks like forEach, for in loop etc. Is there a simple one line code to achieve this in the class property not inside a function.
Lodash
You can use _.zipObject. It accepts two arrays - one for keys, another for values but if you just use the same array twice you'd get matching pairs:
const arr = ["one","two","three"];
const obj = _.zipObject(arr, arr);
console.log(obj);
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.15/lodash.min.js"></script>
Plain JavaScript
You can use Object.fromEntries to do the same thing. It works with an array of key-value pairs, so you'll have to transform yours to that:
const arr = ["one","two","three"];
const matchingKeyValuePairs = arr.map(x => [x, x]);
const obj = Object.fromEntries(matchingKeyValuePairs);
console.log(obj);
Also you can use Array#reduce to generate an object with a computed property name:
const arr = ["one","two","three"];
const obj = arr.reduce((acc, item) => ({...acc, [item]: item}), {});
console.log(obj);
data = ["one","two","three"];
data = data.map(e => [e,e]) // keyvalue pairs [["one","one"],["two","two"],["three","three"]]
data = Object.fromEntries(data); // {"one":"one","two":"two","three":"three"}
map will convert each element of your input array to a structure you want.
In this case, we want to convert each element to an array with the element repeated twice in it
Object.froEntries will convert a list of key-value pair to an Object
This can be also done with the plain old for loop
data = ["one","two","three"];
obj = {};
for(let i = 0; i < data.length ; i++){
obj[data[i]] = data[i];
}
Try this:
const arr = ["one","two","three"]
let obj = {}
arr.forEach(item => {obj[item] = item})
document.write(JSON.stringify(obj))
Lodash has the _.keyBy() function, that creates an object from an array by generating keys from the values via the function supplied (the iteratee). The default iteratee is _.identity(), which returns the value.
const arr = ["one","two","three"];
const obj = _.keyBy(arr);
console.log(obj);
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.15/lodash.min.js"></script>
Looking for help to convert/group an object to an array using a key, the key has a difference with its (-)suffix.
const obj = {
"name-1":"a",
"age-1":"20",
"email-1":"a#email.com",
"name-2":"b",
"age-2":"24",
"email-2":"b#email.com",
"name-3":"c",
"age-3":"22",
"email-3":"c#email1.com"
};
Expected result
[
{
"name":"a",
"age":"20",
"email":"a#email.com"
},
{
"name":"b",
"age":"24",
"email":"b#email.com"
},
{
"name":"c",
"age":"22",
"email":"c#email.com"
}
]
Maybe due wrong search keyword unable to find a duplicate question.
You can run a reduce on Object.entries and split the keys say name-1, age-2 etc by '-' and return an array of objects.
const obj = {
"name-1":"a",
"age-1":"20",
"email-1":"a#email.com",
"name-2":"b",
"age-2":"24",
"email-2":"b#email.com",
"name-3":"c",
"age-3":"22",
"email-3":"c#email1.com"
};
const res = Object.entries(obj).reduce((acc, [key, value]) => {
const [ k, i ] = key.split('-');
acc[i - 1] = acc[i - 1] || {};
acc[i-1][k] = value;
return acc;
}, [])
console.log(res);
At the code above inside the reduce I split the key by '-' and it gives me a key of an object and the index of the final array.
Then I check if the index i - 1 exists in the array. If not then initialized it by an empty object. Here I use i - 1 because the given object keys are starting from 1 but an array starts from 0.
Finally, I put the object value into the newly created object.
This is a nice algorithm question that I will resolve by writing it with ES6 syntax.
You can achieve this thanks to some functions such as Object.entries and reduce
Example:
const obj = {
"name-1":"a",
"age-1":"20",
"email-1":"a#email.com",
"name-2":"b",
"age-2":"24",
"email-2":"b#email.com",
"name-3":"c",
"age-3":"22",
"email-3":"c#email1.com"
};
const result = Object.entries(obj)
// Here we destructure the entry with on the left the key, and value on the right
.reduce((accumulator, [key, value]) => {
const [property, index] = key.split('-');
// Get the value currently being filled, or an empty object if it doesn't
// exist yet.
const entry = accumulator[index] || {};
accumulator[index] = {
// Spread the current entry to which we are adding
// the property to the object being filled
...entry,
// Dynamic key syntax
[property]: value,
};
return accumulator;
}, [])
// Remove "holes" from the array since it's indexed with given keys
.filter(value => value !== undefined);
console.log(result);
I have a JSON object in NoSql database in this format. We are getting this data after migrating some records from some other database and these are multi-valued fields.(Basically we are trying to clean the data for further processing).
{
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
I want to add another key "bpTableDataName" in the same JSON which should have this format and values,
"bpTableDataName": [
{
"name": "aName",
"email": "aEmail",
"pwdid": "aPWID"
},
{
"name": "bName",
"email": "bEmail",
"pwdid": "bPWID"
},
{
"name": "cName",
"email": "cEmail",
"pwdid": "cPWID"
}
],
Is there a way we can achieve this using lodash?
Try following code -
o = {
"BPContName": "aName;bName;cName",
"BPContEmail": "aEmail;bEmail;cEmail",
"BPContPWID": "aPWID;bPWID;cPWID"
}
map = { "BPContName" : "name", "BPContEmail": "email", "BPContPWID": "pwdid" }
const result = _.reduce(o, (arr, v, k) => ( v.split(";").forEach((x,i) => _.set(arr, `${i}.${map[k]}`, x)), arr ), [])
console.log(result)
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.11/lodash.min.js"></script>
You can use split() to split the values into an array.
Then iterate over the array and create the require json and then push that into results.
Check this out.
var data = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
var names = data.BPContName.split(';');
var emails = data.BPContEmail.split(';');
var pwids = data.BPContPWID.split(';');
var results = [];
for(var i = 0 ; i < names.length; i++) {
var obj = {
name: names[i],
email: emails[i],
pwdid: pwids[i]
}
results.push(obj);
}
console.log(results)
You could reduce the entries returned by Object.entries like this:
let obj = {
"BPContName": "aName;bName;cName",
"BPContEmail": "aEmail;bEmail;cEmail",
"BPContPWID": "aPWID;bPWID;cPWID"
}
let bpTableDataName = Object.entries(obj).reduce((r, [key, value]) => {
let splits = value.split(";");
key = key.replace("BPCont", "").toLowerCase();
splits.forEach((split, i) => (r[i] = r[i] || {})[key] = split)
return r;
}, [])
obj.bpTableDataName = bpTableDataName;
console.log(obj)
Object.entries returns an array of key-value pair. Loop through each of them
split the each value at ;
get the key by removing BPCont part and making it lowerCase
Loop through the splits and update specific keys of objects at each index
Update:
Since you have an extra d in the output's key, you can create a mapping object:
propertyMap = {
"BPContName": "name",
"BPContEmail": "email",
"BPContPWID": "pwdid"
}
And inside the reduce, change the replace code to this:
key = propertyMap[key]
Using Object.assign, Object.entries, Array#map and the spread operator make this trivial
const inputdata = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
};
const t1=Object.assign({},...Object.entries(inputdata).map(([k,v])=>({[k]:v.split(';')})));
inputdata.bpTableDataName=t1.BPContName.map((name,i)=>({name,email:t1.BPContEmail[i],pwdid:t1.BPContPWID[i]}));
console.log(inputdata);
Of course, it wouldn't be me without a one-liner
const obj = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
};
// one line to rule them all
obj.bpTableDataName=Object.entries(obj).reduce((r,[k,v])=>(v.split(';').forEach((v,i)=>(r[i]=r[i]||{})[{BPContName:'name',BPContEmail:'email',BPContPWID:'pwdid'}[k]]=v),r),[]);
//
console.log(obj);
Basically what you need is to zip it.
Snippet:
let obj = {"BPContName":"aName;bName;cName","BPContEmail":"aEmail;bEmail;cEmail","BPContPWID":"aPWID;bPWID;cPWID"},
res = _.zipWith(
..._.map(obj, v => v.split(';')),
(name, email, pwid) => ({name, email, pwid})
);
console.log(res)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
Note, the sequence of the parameters we have to put such a way, the original object give us values when using Object.values or giving us keys when using Object.keys usually it is alphabetical order. But, In case in any env the order is not guranted we can sort it with a sequence of keys as a metadata.
Or else you can explicitly pass the arguments like:
(obj.BPContName.split(';'), obj.BPContEmail.split(';'), obj.BPContPWID.split(';'))
You can use lodash's _.flow() to create a function. Use _.map() with _.overArgs() to create a function that splits the values, format the key, and then converts them to an array of pairs using _.unzip(), for example [['name', 'x'], ['name', 'y']]. Transpose the array of arrays with _.unzip() to combine pairs of different properties. Then use _.map() to iterate, and convert each array of pairs to an object using _.fromPairs().
const { flow, partialRight: pr, map, unzip, overArgs, times, size, constant, split, fromPairs } = _
const keysMap = new Map([['BPContName', 'name'], ['BPContEmail', 'email'], ['BPContPWID', 'pwdid']])
const formatKey = key => keysMap.get(key)
const splitVals = pr(split, ';')
const fn = flow(
pr(map, overArgs(
(vals, k) => unzip([vals, times(size(vals), constant(k))]),
[splitVals, formatKey])
),
unzip, // transpose
pr(map, fromPairs) // convert each pairs array to object
)
const data = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
const results = fn(data)
console.log(results)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>