A guide to organizing elements in Javascript to calculate the Cartesian product in Javascript

Question

A guide to organizing elements in Javascript to calculate the Cartesian product in Javascript

I encountered a situation where I have an object structured like this:

   [
    {attributeGroupId:2, attributeId: 11, name: 'Diamond'},
    {attributeGroupId:1, attributeId: 9, name: '916'},
    {attributeGroupId:1, attributeId: 1, name: '24K'},
    {attributeGroupId:2, attributeId: 12, name: 'Square'}
]

The expected output should be:

[
    {attributeGroupId:2, attributeId: 11, name: 'Diamond'},
    {attributeGroupId:2, attributeId: 12, name: 'Square'}
]

,

[
    {attributeGroupId:1, attributeId: 9, name: '916'},
    {attributeGroupId:1, attributeId: 1, name: '24K'}
]

This allows me to perform the cartesian product as demonstrated below:

[
     {attributeId: 11-9, name: 'Diamond-916'}, 
     {attributeId: 11-1, name: 'Diamond-24K'},
     {attributeId: 12-9, name: 'Square-916'}, 
     {attributeId: 12-1, name: 'Square-24K'},
]

Now, the goal is to maintain this functionality in a versatile manner since the number of attributeGroupId values can vary during runtime.

I propose that dividing the array into smaller arrays based on attributeGroupId would serve as the initial step.

javascript algorithm cartesian-product

Answer 1

Answer №1

If you need to create a simple filter function, you can use the following code snippet:

function basicFilter(data, id) {
  return data.filter((item) => item.id === id);
}

console.log(basicFilter(data, 1)) //returns elements with id = 1
console.log(basicFilter(data, 2)) //returns elements with id = 2

This code presents a more general solution that returns an array of filtered arrays:

function advancedFilter(data) {
  const mem = {};
  data.forEach((item) => {
    if (mem[item.id]) {
      mem[item.id].push(item);
    } else {
      mem[item.id] = [item];
    }
  })
  return Object.values(mem);
}

Update based on received feedback: For scenarios where attribute order is irrelevant, this code snippet provides a way to obtain the "cartesian concatenation" of multiple arrays:

function concatArrays(arrays) {
  if (arrays.length <= 1 ) return arrays[0];
  const first = arrays[0];
  const second = concatArrays(arrays.slice(1));
  const result = [];
   first.forEach(( itemFirst ) => {
      second.forEach( (itemSecond) => {
        result.push({id: `${itemFirst.id}-${itemSecond.id}`, name: `${itemFirst.name}-${itemSecond.name}`})
      });
   });
   return result;
}

By using the following call:

console.log(concatArrays(advancedFilter(data)));

You will receive the expected output, even though the strings may be concatenated differently:

[
  {
    "id":"9-11",
    "name":"916-Diamond"
  },
  {
    "id":"9-12",
    "name":"916-Square"
  },
  {
    "id":"1-11",
    "name":"24K-Diamond"
  },
  {
    "id":"1-12",
    "name":"24K-Square"
  }
]

Answer 2

If you need to create a simple filter function, you can use the following code snippet:

function basicFilter(data, id) {
  return data.filter((item) => item.id === id);
}

console.log(basicFilter(data, 1)) //returns elements with id = 1
console.log(basicFilter(data, 2)) //returns elements with id = 2

This code presents a more general solution that returns an array of filtered arrays:

function advancedFilter(data) {
  const mem = {};
  data.forEach((item) => {
    if (mem[item.id]) {
      mem[item.id].push(item);
    } else {
      mem[item.id] = [item];
    }
  })
  return Object.values(mem);
}

Update based on received feedback: For scenarios where attribute order is irrelevant, this code snippet provides a way to obtain the "cartesian concatenation" of multiple arrays:

function concatArrays(arrays) {
  if (arrays.length <= 1 ) return arrays[0];
  const first = arrays[0];
  const second = concatArrays(arrays.slice(1));
  const result = [];
   first.forEach(( itemFirst ) => {
      second.forEach( (itemSecond) => {
        result.push({id: `${itemFirst.id}-${itemSecond.id}`, name: `${itemFirst.name}-${itemSecond.name}`})
      });
   });
   return result;
}

By using the following call:

console.log(concatArrays(advancedFilter(data)));

You will receive the expected output, even though the strings may be concatenated differently:

[
  {
    "id":"9-11",
    "name":"916-Diamond"
  },
  {
    "id":"9-12",
    "name":"916-Square"
  },
  {
    "id":"1-11",
    "name":"24K-Diamond"
  },
  {
    "id":"1-12",
    "name":"24K-Square"
  }
]

Answer 3

Answer №2

In my opinion, breaking down this logic into smaller pieces would be more beneficial. Initially, creating a function that can generate a cartesian product for an array of arrays would prove to be valuable. Let's create a utility function for that purpose. Additionally, it is common to split an array into subarrays based on a shared feature. So, let's also create a function for that.

Subsequently, we can develop a basic main function that groups the IDs by attributeGroupId, and then applies the cartesian product to each item in the resulting array:

[
  {attributeGroupId: 2, attributeId: 11, name: "Diamond"},
  {attributeGroupId: 1, attributeId: 9, name: "916"}
]

We can then construct a new object by combining the properties of attributeId and name.

const cartesian = ([xs, ...xss]) =>
  xs == undefined ? [[]] : xs .flatMap (x => cartesian (xss) .map (ys => [x, ...ys]))

const group = (fn, k) => (xs) => Object .values (xs .reduce (
  (a, x) => ((k = 'x' + fn (x)), (a [k] = a [k] || []), (a [k] .push (x)), a), {}
))

const regroupAtts = (xs) => 
  cartesian (group (x => x .attributeGroupId) (xs))
    .map (xs => ({
      attributeId: xs .map (x => x .attributeId) .join ('-'),
      name: xs .map (x => x.name) .join ('-')
    }))

const atts = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}]
const atts2 = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 3, attributeId: 101, name: 'foo'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 3, attributeId: 102, name: 'bar'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}, {attributeGroupId: 3, attributeId: 103, name: 'baz'}]


console .log ('Original:', regroupAtts (atts))
console .log ('With third group added:', regroupAtts (atts2))

.as-console-wrapper {max-height: 100% !important; top: 0}

To demonstrate scalability, a third attribute with entries named "foo", "bar", and "baz" has been included. This showcases how the functionality extends to accommodate additional attributes. However, it is crucial to consider combinatorial explosions when adding numerous attributes, although the code is structured to manage such scenarios.

An intriguing concept derived from this is the potential parameterization of names such as "attributeGroupId", "attributeId", and "name". This could be achieved through the following method:

const regroup = (key, props) => (xs) => 
  cartesian (group (x => x [key]) (xs))
    .map (xs => Object .fromEntries (
      props .map (prop => [prop, xs .map (x => x [prop]) .join ('-')])
    ))

const regroupAtts = regroup ('attributeGroupId', ['attributeId', 'name'])

const cartesian = ([xs, ...xss]) =>
  xs == undefined ? [[]] : xs .flatMap (x => cartesian (xss) .map (ys => [x, ...ys]))

const group = (fn, k) => (xs) => Object .values (xs .reduce (
  (a, x) => ((k = 'x' + fn (x)), (a [k] = a[k] || []), (a[k] .push (x)), a), {}
))

const regroup = (key, props) => (xs) => 
  cartesian (group (x => x [key]) (xs))
    .map (xs => Object .fromEntries (
      props .map (prop => [prop, xs .map (x => x [prop]) .join ('-')])
    ))

const regroupAtts = regroup ('attributeGroupId', ['attributeId', 'name']) 


const atts = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}]
const atts2 = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 3, attributeId: 101, name: 'foo'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 3, attributeId: 102, name: 'bar'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}, {attributeGroupId: 3, attributeId: 103, name: 'baz'}]

console .log ('Original:', regroupAtts (atts))
console .log ('With third group added:', regroupAtts (atts2))

.as-console-wrapper {max-height: 100% !important; top: 0}

This approach allows us to utilize reusable functions like cartesian and group, which are commonly used. These functions have been borrowed from my previous responses, although I made some modifications to the group function by appending the string 'x' before key generation. This adjustment ensures that the keys (attributeGroupIds) are ordered as per your preferences. By exploring this variation, I am assessing whether it could replace the standard function in my toolkit.

Answer 4

In my opinion, breaking down this logic into smaller pieces would be more beneficial. Initially, creating a function that can generate a cartesian product for an array of arrays would prove to be valuable. Let's create a utility function for that purpose. Additionally, it is common to split an array into subarrays based on a shared feature. So, let's also create a function for that.

Subsequently, we can develop a basic main function that groups the IDs by attributeGroupId, and then applies the cartesian product to each item in the resulting array:

[
  {attributeGroupId: 2, attributeId: 11, name: "Diamond"},
  {attributeGroupId: 1, attributeId: 9, name: "916"}
]

We can then construct a new object by combining the properties of attributeId and name.

const cartesian = ([xs, ...xss]) =>
  xs == undefined ? [[]] : xs .flatMap (x => cartesian (xss) .map (ys => [x, ...ys]))

const group = (fn, k) => (xs) => Object .values (xs .reduce (
  (a, x) => ((k = 'x' + fn (x)), (a [k] = a [k] || []), (a [k] .push (x)), a), {}
))

const regroupAtts = (xs) => 
  cartesian (group (x => x .attributeGroupId) (xs))
    .map (xs => ({
      attributeId: xs .map (x => x .attributeId) .join ('-'),
      name: xs .map (x => x.name) .join ('-')
    }))

const atts = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}]
const atts2 = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 3, attributeId: 101, name: 'foo'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 3, attributeId: 102, name: 'bar'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}, {attributeGroupId: 3, attributeId: 103, name: 'baz'}]


console .log ('Original:', regroupAtts (atts))
console .log ('With third group added:', regroupAtts (atts2))

.as-console-wrapper {max-height: 100% !important; top: 0}

To demonstrate scalability, a third attribute with entries named "foo", "bar", and "baz" has been included. This showcases how the functionality extends to accommodate additional attributes. However, it is crucial to consider combinatorial explosions when adding numerous attributes, although the code is structured to manage such scenarios.

An intriguing concept derived from this is the potential parameterization of names such as "attributeGroupId", "attributeId", and "name". This could be achieved through the following method:

const regroup = (key, props) => (xs) => 
  cartesian (group (x => x [key]) (xs))
    .map (xs => Object .fromEntries (
      props .map (prop => [prop, xs .map (x => x [prop]) .join ('-')])
    ))

const regroupAtts = regroup ('attributeGroupId', ['attributeId', 'name'])

const cartesian = ([xs, ...xss]) =>
  xs == undefined ? [[]] : xs .flatMap (x => cartesian (xss) .map (ys => [x, ...ys]))

const group = (fn, k) => (xs) => Object .values (xs .reduce (
  (a, x) => ((k = 'x' + fn (x)), (a [k] = a[k] || []), (a[k] .push (x)), a), {}
))

const regroup = (key, props) => (xs) => 
  cartesian (group (x => x [key]) (xs))
    .map (xs => Object .fromEntries (
      props .map (prop => [prop, xs .map (x => x [prop]) .join ('-')])
    ))

const regroupAtts = regroup ('attributeGroupId', ['attributeId', 'name']) 


const atts = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}]
const atts2 = [{attributeGroupId: 2, attributeId: 11, name: 'Diamond'}, {attributeGroupId: 1, attributeId: 9, name: '916'}, {attributeGroupId: 3, attributeId: 101, name: 'foo'}, {attributeGroupId: 1, attributeId: 1, name: '24K'}, {attributeGroupId: 3, attributeId: 102, name: 'bar'}, {attributeGroupId: 2, attributeId: 12, name: 'Square'}, {attributeGroupId: 3, attributeId: 103, name: 'baz'}]

console .log ('Original:', regroupAtts (atts))
console .log ('With third group added:', regroupAtts (atts2))

.as-console-wrapper {max-height: 100% !important; top: 0}

This approach allows us to utilize reusable functions like cartesian and group, which are commonly used. These functions have been borrowed from my previous responses, although I made some modifications to the group function by appending the string 'x' before key generation. This adjustment ensures that the keys (attributeGroupIds) are ordered as per your preferences. By exploring this variation, I am assessing whether it could replace the standard function in my toolkit.

A guide to organizing elements in Javascript to calculate the Cartesian product in Javascript

Answer №1

Answer №2

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