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fix(curriculum): Use the reduce Method to Analyze Data (#34315)

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Aditya
2018-11-22 22:44:31 +05:30
committed by Valeriy
parent a9f4f11a77
commit a489ac9df8
1 changed files with 135 additions and 9 deletions
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curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.english.md
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@ -14,7 +14,7 @@ However, before we get there, let's practice using <code>reduce</code> first.
## Instructions
<section id='instructions'>
The variable <code>watchList</code> holds an array of objects with information on several movies. Use <code>reduce</code> to find the average IMDB rating of the movies <strong>directed by Christopher Nolan</strong>. Recall from prior challenges how to <code>filter</code> data and <code>map</code> over it to pull what you need. You may need to create other variables, but save the final average into the variable <code>averageRating</code>. Note that the rating values are saved as strings in the object and need to be converted into numbers before they are used in any mathematical operations.
The variable <code>watchList</code> holds an array of objects with information on several movies. Use <code>reduce</code> to find the average IMDB rating of the movies <strong>directed by Christopher Nolan</strong>. Recall from prior challenges how to <code>filter</code> data and <code>map</code> over it to pull what you need. You may need to create other variables, and return the average rating from <code>getRating</code> function. Note that the rating values are saved as strings in the object and need to be converted into numbers before they are used in any mathematical operations.
</section>
## Tests
@ -26,10 +26,12 @@ tests:
testString: assert(watchList[0].Title === "Inception" && watchList[4].Director == "James Cameron", 'The <code>watchList</code> variable should not change.');
- text: Your code should use the <code>reduce</code> method.
testString: assert(code.match(/\.reduce/g), 'Your code should use the <code>reduce</code> method.');
- text: The <code>averageRating</code> should equal 8.675.
testString: assert(averageRating == 8.675, 'The <code>averageRating</code> should equal 8.675.');
- text: The <code>getRating(watchList)</code> should equal 8.675.
testString: assert(getRating(watchList) === 8.675, 'The <code>getRating(watchList)</code> should equal 8.675.');
- text: Your code should not use a <code>for</code> loop.
testString: assert(!code.match(/for\s*?\(.*\)/g), 'Your code should not use a <code>for</code> loop.');
- text: Your code should return correct output after modifying the <code>watchList</code> object.
testString: assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55, 'Your code should return correct output after modifying the <code>watchList</code> object');
```
@ -155,13 +157,15 @@ var watchList = [
}
];
// Add your code below this line
function getRating(watchList){
// Add your code below this line
var averageRating;
var averageRating;
// Add your code above this line
console.log(averageRating);
// Add your code above this line
return averageRating;
}
console.log(getRating(watchList));
```
</div>
@ -174,6 +178,128 @@ console.log(averageRating);
<section id='solution'>
```js
// solution required
// the global variable
var watchList = [
{
"Title": "Inception",
"Year": "2010",
"Rated": "PG-13",
"Released": "16 Jul 2010",
"Runtime": "148 min",
"Genre": "Action, Adventure, Crime",
"Director": "Christopher Nolan",
"Writer": "Christopher Nolan",
"Actors": "Leonardo DiCaprio, Joseph Gordon-Levitt, Ellen Page, Tom Hardy",
"Plot": "A thief, who steals corporate secrets through use of dream-sharing technology, is given the inverse task of planting an idea into the mind of a CEO.",
"Language": "English, Japanese, French",
"Country": "USA, UK",
"Awards": "Won 4 Oscars. Another 143 wins & 198 nominations.",
"Poster": "http://ia.media-imdb.com/images/M/MV5BMjAxMzY3NjcxNF5BMl5BanBnXkFtZTcwNTI5OTM0Mw@@._V1_SX300.jpg",
"Metascore": "74",
"imdbRating": "8.8",
"imdbVotes": "1,446,708",
"imdbID": "tt1375666",
"Type": "movie",
"Response": "True"
},
{
"Title": "Interstellar",
"Year": "2014",
"Rated": "PG-13",
"Released": "07 Nov 2014",
"Runtime": "169 min",
"Genre": "Adventure, Drama, Sci-Fi",
"Director": "Christopher Nolan",
"Writer": "Jonathan Nolan, Christopher Nolan",
"Actors": "Ellen Burstyn, Matthew McConaughey, Mackenzie Foy, John Lithgow",
"Plot": "A team of explorers travel through a wormhole in space in an attempt to ensure humanity's survival.",
"Language": "English",
"Country": "USA, UK",
"Awards": "Won 1 Oscar. Another 39 wins & 132 nominations.",
"Poster": "http://ia.media-imdb.com/images/M/MV5BMjIxNTU4MzY4MF5BMl5BanBnXkFtZTgwMzM4ODI3MjE@._V1_SX300.jpg",
"Metascore": "74",
"imdbRating": "8.6",
"imdbVotes": "910,366",
"imdbID": "tt0816692",
"Type": "movie",
"Response": "True"
},
{
"Title": "The Dark Knight",
"Year": "2008",
"Rated": "PG-13",
"Released": "18 Jul 2008",
"Runtime": "152 min",
"Genre": "Action, Adventure, Crime",
"Director": "Christopher Nolan",
"Writer": "Jonathan Nolan (screenplay), Christopher Nolan (screenplay), Christopher Nolan (story), David S. Goyer (story), Bob Kane (characters)",
"Actors": "Christian Bale, Heath Ledger, Aaron Eckhart, Michael Caine",
"Plot": "When the menace known as the Joker wreaks havoc and chaos on the people of Gotham, the caped crusader must come to terms with one of the greatest psychological tests of his ability to fight injustice.",
"Language": "English, Mandarin",
"Country": "USA, UK",
"Awards": "Won 2 Oscars. Another 146 wins & 142 nominations.",
"Poster": "http://ia.media-imdb.com/images/M/MV5BMTMxNTMwODM0NF5BMl5BanBnXkFtZTcwODAyMTk2Mw@@._V1_SX300.jpg",
"Metascore": "82",
"imdbRating": "9.0",
"imdbVotes": "1,652,832",
"imdbID": "tt0468569",
"Type": "movie",
"Response": "True"
},
{
"Title": "Batman Begins",
"Year": "2005",
"Rated": "PG-13",
"Released": "15 Jun 2005",
"Runtime": "140 min",
"Genre": "Action, Adventure",
"Director": "Christopher Nolan",
"Writer": "Bob Kane (characters), David S. Goyer (story), Christopher Nolan (screenplay), David S. Goyer (screenplay)",
"Actors": "Christian Bale, Michael Caine, Liam Neeson, Katie Holmes",
"Plot": "After training with his mentor, Batman begins his fight to free crime-ridden Gotham City from the corruption that Scarecrow and the League of Shadows have cast upon it.",
"Language": "English, Urdu, Mandarin",
"Country": "USA, UK",
"Awards": "Nominated for 1 Oscar. Another 15 wins & 66 nominations.",
"Poster": "http://ia.media-imdb.com/images/M/MV5BNTM3OTc0MzM2OV5BMl5BanBnXkFtZTYwNzUwMTI3._V1_SX300.jpg",
"Metascore": "70",
"imdbRating": "8.3",
"imdbVotes": "972,584",
"imdbID": "tt0372784",
"Type": "movie",
"Response": "True"
},
{
"Title": "Avatar",
"Year": "2009",
"Rated": "PG-13",
"Released": "18 Dec 2009",
"Runtime": "162 min",
"Genre": "Action, Adventure, Fantasy",
"Director": "James Cameron",
"Writer": "James Cameron",
"Actors": "Sam Worthington, Zoe Saldana, Sigourney Weaver, Stephen Lang",
"Plot": "A paraplegic marine dispatched to the moon Pandora on a unique mission becomes torn between following his orders and protecting the world he feels is his home.",
"Language": "English, Spanish",
"Country": "USA, UK",
"Awards": "Won 3 Oscars. Another 80 wins & 121 nominations.",
"Poster": "http://ia.media-imdb.com/images/M/MV5BMTYwOTEwNjAzMl5BMl5BanBnXkFtZTcwODc5MTUwMw@@._V1_SX300.jpg",
"Metascore": "83",
"imdbRating": "7.9",
"imdbVotes": "876,575",
"imdbID": "tt0499549",
"Type": "movie",
"Response": "True"
}
];
function getRating(watchList){
var averageRating;
const rating = watchList
.filter(obj => obj.Director === "Christopher Nolan")
.map(obj => Number(obj.imdbRating));
averageRating = rating.reduce((accum, curr) => accum + curr)/rating.length;
return averageRating;
}
```
</section>