185 lines
3.6 KiB
Markdown
185 lines
3.6 KiB
Markdown
---
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id: 587d8253367417b2b2512c6d
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title: Perform an Intersection on Two Sets of Data
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challengeType: 1
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forumTopicId: 301709
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dashedName: perform-an-intersection-on-two-sets-of-data
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---
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# --description--
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In this exercise we are going to perform an intersection on 2 sets of data. We will create a method on our `Set` data structure called `intersection`. An intersection of sets represents all values that are common to two or more sets. This method should take another `Set` as an argument and return the `intersection` of the two sets.
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For example, if `setA = ['a','b','c']` and `setB = ['a','b','d','e']`, then the intersection of setA and setB is: `setA.intersection(setB) = ['a', 'b']`.
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# --hints--
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Your `Set` class should have a `intersection` method.
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```js
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assert(
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(function () {
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var test = new Set();
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return typeof test.intersection === 'function';
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})()
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);
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```
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The proper collection should be returned.
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```js
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assert(
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(function () {
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var setA = new Set();
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var setB = new Set();
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setA.add('a');
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setA.add('b');
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setA.add('c');
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setB.add('c');
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setB.add('d');
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var intersectionSetAB = setA.intersection(setB);
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return (
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intersectionSetAB.size() === 1 && intersectionSetAB.values()[0] === 'c'
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);
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})()
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);
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```
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# --seed--
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## --seed-contents--
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```js
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class Set {
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constructor() {
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// This will hold the set
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this.dictionary = {};
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this.length = 0;
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}
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// This method will check for the presence of an element and return true or false
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has(element) {
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return this.dictionary[element] !== undefined;
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}
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// This method will return all the values in the set
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values() {
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return Object.keys(this.dictionary);
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}
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// This method will add an element to the set
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add(element) {
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if (!this.has(element)) {
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this.dictionary[element] = true;
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this.length++;
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return true;
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}
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return false;
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}
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// This method will remove an element from a set
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remove(element) {
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if (this.has(element)) {
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delete this.dictionary[element];
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this.length--;
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return true;
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}
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return false;
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}
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// This method will return the size of the set
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size() {
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return this.length;
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}
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// This is our union method
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union(set) {
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const newSet = new Set();
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this.values().forEach(value => {
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newSet.add(value);
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})
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set.values().forEach(value => {
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newSet.add(value);
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})
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return newSet;
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}
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// Only change code below this line
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// Only change code above this line
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}
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```
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# --solutions--
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```js
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class Set {
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constructor() {
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this.dictionary = {};
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this.length = 0;
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}
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has(element) {
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return this.dictionary[element] !== undefined;
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}
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values() {
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return Object.keys(this.dictionary);
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}
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add(element) {
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if (!this.has(element)) {
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this.dictionary[element] = true;
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this.length++;
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return true;
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}
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return false;
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}
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remove(element) {
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if (this.has(element)) {
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delete this.dictionary[element];
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this.length--;
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return true;
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}
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return false;
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}
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size() {
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return this.length;
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}
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union(set) {
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const newSet = new Set();
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this.values().forEach(value => {
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newSet.add(value);
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})
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set.values().forEach(value => {
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newSet.add(value);
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})
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return newSet;
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}
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intersection(set) {
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const newSet = new Set();
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let largeSet;
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let smallSet;
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if (this.dictionary.length > set.length) {
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largeSet = this;
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smallSet = set;
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} else {
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largeSet = set;
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smallSet = this;
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}
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smallSet.values().forEach(value => {
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if (largeSet.dictionary[value]) {
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newSet.add(value);
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}
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})
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return newSet;
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}
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}
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```
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