I am wondering how .reduce((sumRate,rate) => sumRate + rate) knows to assign the sum of imdbRatings to sumRate. I don’t see where it links. Please help, Thank you!!!
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I am wondering how .reduce((sumRate,rate) => sumRate + rate) knows to assign the sum of imdbRatings to sumRate. I don’t see where it links. Please help, Thank you!!!
Your code so far
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function getRating(watchList){
// Add your code below this line
const averageRating = watchList
// Use filter to find films directed by Christopher Nolan
.filter(film => film.Director === "Christopher Nolan")
// Use map to convert their ratings from strings to numbers
.map(film => Number(film.imdbRating))
// Use reduce to add together their ratings
.reduce((sumOfRatings, rating) => sumOfRatings + rating) /
// Divide by the number of Nolan films to get the average rating
watchList.filter(film => film.Director === "Christopher Nolan").length;
// Add your code above this line
return averageRating;
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I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
I assume you know how map and filter work since they are covered in lessons before this. If you check the documentation it gives a much more detailed explanation of how reduce works.
I am sorry I don’t have the answer to your question I just wanted to post my unique answer here since I can’t find a way to do that in free code camp
Anyway, here is it.
function getRating(watchList) {
// Only change code below this line
let averageRating = watchList
// gets the movies produced by Christopher Nolan
.filter(movie => movie.Director === "Christopher Nolan")
//gets the average with the callback function having all
// four arguments and the
// index must be included because without it will return NaN.
// I don't know the
// reason though I will be happy to know why
.reduce((avg, movie, index, array) => {
avg + parseFloat(movie.imdbRating) / array.length, 0 )
}
// In the first iteration the avg = 0 + movie.imdbRating
// of the first movie / array.length = 5
// the result of the first iteration becomes the value of
// the avg in the second
//interation and so on... till the last iteration where we get
// the avg(average).
// for example the 5 values (1, 2, 3, 4, 5)
// will be 0 +1/5 => 1/5 + 2/5 => 3/5 + 3/5 =>
// 6/5 + 4/5 => 2 + 4/5 = 3
// Only change code above this line
return averageRating;
}
