Reputation: 630
I have two arrays:
alphabet
is composed of letters (e.g. the English alphabet). dictionary
is a list of objects with words and definitions, 'word'
being the key for the word value.
I want to build a new array called frequency
which would contain the number of words that start with each letter in the alphabet array, with indices corresponding to the alphabet array.
I've managed to come up with the following:
alphabet.forEach(function(letter) {
frequency = dictionary.filter(item => item['word'].toLowerCase().startsWith(letter)).length;
});
This gets me individual values for frequency
. What is the best syntax in Javascript for building an array of those values? Is it another filter? Or should the code use the current forEach
manually with a incremental index?
Upvotes: 0
Views: 82
Reputation: 1298
Using reduce, you can easily make a new object with the letter as the key and an array of matches as the value.
const words = ["abba", "ant", "apple", "bannana", "barn", "car", "cat"];
const alphabet = "abcdefghijklmnopqrstuvwxyz".split("");
const result = alphabet.reduce((a, letter) => {
a[letter] = words.filter(word => word.toLowerCase().startsWith(letter));
return a;
}, {});
console.log(result);
Upvotes: 1
Reputation: 2205
First, let's get some example data. We'll ignore anything that isn't related to the question.
const alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('')
var dictionary = [{'word': 'alpha'}, {'word': 'beta'}, {'word': 'balloon'}]
Then we'll create a results
variable, which will hold an array of all results in alphabetical order.
var results = []
Now we loop over the same way you did before, but we'll push
each result to our list.
alphabet.forEach(function(letter) {
frequency = dictionary.filter(item => item['word'].toLowerCase().startsWith(letter)).length;
results.push(frequency);
});
As an alternative solution that allows us to more easily look through our results, we'll make results an object, and use letters as keys.
var results = {};
alphabet.forEach(function(letter) {
frequency = dictionary.filter(item => item['word'].toLowerCase().startsWith(letter)).length;
results[letter] = frequency;
});
Upvotes: 1