Convert combination of object from Object-CodePudding

I want to covert combination of object from an object. For example:

Example:

    var obj1 = {city: "Canada", pincode: [300005, 300006, 300007], locations: ["Toronto", "Winnipeg", "Montreal"]};

Expected Output is:

    result = [{city: "Canada", pincode: 300005, location: "Toronto"}, {city: "Canada", pincode: 300005, location: "Winnipeg"}, {city: "Canada", pincode: 300005, location: "Montreal"}, {city: "Canada", pincode: 300006, location: "Toronto"}, {city: "Canada", pincode: 300006, location: "Winnipeg"}, {city: "Canada", pincode: 300006, location: "Montreal"},{city: "Canada", pincode: 300007, location: "Toronto"}, {city: "Canada", pincode: 300007, location: "Winnipeg"}, {city: "Canada", pincode: 300007, location: "Montreal"}]

CodePudding user response：

Try this -> Map through pincodes and locartions and return the required object for each pincode and location.

var obj1 = { city: "Canada", pincode: [300005, 300006, 300007], locations: ["Toronto", "Winnipeg", "Montreal"] };

//map through the pincodes and locations
const resultArray = obj1.pincode.map((pincode) => {
  return obj1.locations.map((location, index) => {
    return { city: obj1.city, pincode: pincode, location: obj1.locations[index] }
  })
});
//flatten the result array 
[].concat.apply([], resultArray);

CodePudding user response：

const result = [];
 var obj1 = {city: "Canada", pincode: [300005, 300006, 300007], locations: ["Toronto", "Winnipeg", "Montreal"]};
 obj1.pincode.map((val, idx) => {
     result.push({
         city: obj1.city,
         pincode: val,
         locations: obj1.locations[idx]
     })
 });

CodePudding user response：

Here is a generic solution, which assumes that all the array typed properties will be broken down into array-elements, making a Cartesian product when more than one array is found in the given object.

It reuses code for cartesian product of arrays, and defines a few more helper functions:

toArray to wrap the argument into an array if it isn't one yet, or else just return the argument as-is. This is used to have an array version of all property values in the given object, and these arrays are passed on to get a cartesion product
zip to merge two equally-sized arrays into one array of pairs. This is used by combine:
combine to merge an array of keys and an array of values into one object. The values are those that come back from the cartesian product.

const cartesian = 
    data => data.reduce((a, b) => a.flatMap(x => b.map(y => [...x, y])), [[]]);
const toArray = a => [].concat(a);
const zip = (a, b) => a.map((v, i) => [v, b[i]]);
const combine = (keys, values) => Object.fromEntries(zip(keys, values));
// The main algorithm:
const expand = obj =>
    cartesian(Object.values(obj).map(toArray)).map(combine.bind(null, Object.keys(obj)));


// Example
const obj1 = {
    city: "Canada", 
    pincode: [300005, 300006, 300007], 
    locations: ["Toronto", "Winnipeg", "Montreal"]
}
const result = expand(obj1);
console.log(result);

So the steps performed are:

Take the values from the given object
Make them arrays is they are not yet, so "Canada" becomes ["Canada"]
Perform the Cartesian product on those arrays
Merge each combination from that product with the keys of the original object to turn that combination into an object