I Have an array of arrays and would like to return a dictionary like so.
function retFunc(array) {
var dict ={};
for(var i=0; i<=array.length-1;i++){
dict={[array[i][0]] : array[i][1]}
}
return dict
}
retFunc([['a','b'],'['c','d']])
output
{ c : 'd'}
the return dict only returns the last key/value pair. I would like to return all key/value pairs but doing something like dict += {[array[i][0]] : array[i][1]} doesn't work.
You are doing
dict={[array[i][0]] : array[i][1]}
That means you assign a new object to variable dict. Not appending! If you want to append to your dict object. Write this:
dict[array[i][0]] = array[i][1];
It's very simple with Object.assign, .map(), spread syntax, and parameter destructuring:
function retFunc(arr) {
return Object.assign({}, ...arr.map(([k, v]) => ({[k]: v})));
}
console.log(retFunc([['a','b'],['c','d']]));you would have to do
function retFunc(array) {
var dict ={};
for(var i=0; i<=array.length-1;i++){
dict[array[i][0]] = array[i][1];
}
return dict
}
console.log(retFunc([['a','b'],['c','d']]))Instead use dict[array[i][0]] = array[i][1]; to map all key values.
function retFunc(array) {
var dict ={};
for(var i=0; i<=array.length-1;i++){
dict[array[i][0]] = array[i][1];
}
return dict
}
var x = retFunc([['a','b'],['c','d']]);
console.log(x);Try like this with object key = value assignment,
function retFunc(array) {
var dict = {};
for (var i = 0; i <= array.length - 1; i++) {
dict[array[i][0]] = array[i][1];
}
return dict;
}
console.log(retFunc([
['a', 'b'],
['c', 'd']
]));
Use assignment as dict[array[i][0]] = array[i][1] to add a key:value pair to your dict Object
Remove the typo as well from the array.
function retFunc(array) {
var dict = {};
for (var i = 0; i <= array.length - 1; i++) {
dict[array[i][0]] = array[i][1]
}
return dict
}
console.log(retFunc([
['a', 'b'],
['c', 'd']
]))This is a perfect candidate for the Array.reduce function. Below is a commented example that shows how Array.reduce works for your example. You can also find documentation at MDN
const input = [
['a', 'b'],
['d', 'd'],
['e', 'f'],
];
// adds key/value from `arr` to dict.
function arrayToDict(dict, arr){
dict = dict || {};
// take an array of two items and turn it into a key value pair.
let [key, value] = arr;
// if you don't like es6 syntax, then this is equivalent
/*
var key = arr[0];
var value = arr[1];
*/
dict[key] = value;
return dict;
}
// this function can be used to add any one of our pairs to a dictionary
console.log('Example1: ', arrayToDict({}, ['a', 'b']));
// now we can use the Array Reduce function to add each pair to the dictionary.
let output = input.reduce(arrayToDict, {});
console.log('Output:', output);You could use a direct assignment to the wanted key.
dict[array[i][0]] = array[i][1];
function retFunc(array) {
var dict = {};
for (var i = 0; i <= array.length - 1; i++) {
dict[array[i][0]] = array[i][1];
}
return dict;
}
console.log(retFunc([['a', 'b'], ['c', 'd']]));A more functional approach could include
Object.assign for collecting parts of an object,
spread syntax ... for taking an array as parameters
Array#map for getting a new array,
destructuring assignment for having the values of an object instead of using an array, and
computed property names to use a variable as key.
function retFunc(array) {
return Object.assign(...array.map(([k, v]) => ({ [k]: v })));
}
console.log(retFunc([['a', 'b'], ['c', 'd']]));The Object.fromEntries() method transforms a list of key-value pairs into an object. link
Object.fromEntries(iterable);
var array = [
['a','b'],
['c','d']
];
var dict = Object.fromEntries(array);
console.log(dict);
// {a: "b", c: "d"}
