Reducing Javascript sub array to single array

Question

I have a result of the following code

 d3.csv("../hello.csv", function(data) {
    console.log(data);
    var usable = data.map(function (d) {
        return {    
            description: d.description.split(" ")
        };
    });
    console.log(usable);
});

the console log of the usable is [object, object, object] when I expand it is

0:Object
  description: Array[3]
    0 : "A"
    1 : "B"
    2 : "C"

1:Object
  description: Array[3]
    0 : "D"
    1 : "E"
    2 : "FG"

2:Object
  description: Array[5]
    0 : "AD"
    1 : "BD"
    2 : "DC"
    4 : "HH"

What I need is single array as follows:

[A,B,C,D,E,FG,AD,BD,DC,HH]

with all elements reduced to single array rather than having multiple.

How can I achieve this? Any help would be highly appreciated.

You should be able to push (w3schools.com/jsref/jsref_push.asp) the elements of one array to another or combine (w3schools.com/jsref/jsref_concat_array.asp) the two outside of D3 and use it — Alexey Ayzin
– Alexey Ayzin, Commented Jun 7, 2016 at 15:45

helderdarocha · Accepted Answer · 2016-06-07 15:59:22Z

2

You can flatten the array using D3.merge(). Assume these are your objects:

var obj1 = {description: [1,2,3]}
var obj2 = {description: [10,20,30,40]};
var obj3 = {description: [100,200,300,400,500]};

var array = [obj1, obj2, obj3]; // your array

So this produces the output you described:

console.log("array", array);

You can use d3.merge(array) to merge several arrays into one:

var flattened = d3.merge([obj1.description, obj2.description, obj3.description]);
console.log("flattened", flattened);

It will print:

flattened [1, 2, 3, 10, 20, 30, 40, 100, 200, 300, 400, 500]

See: JSFiddle

answered Jun 7, 2016 at 15:59

helderdarocha

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Comments

Ezequiel Muns · Accepted Answer · 2016-06-07 16:03:24Z

1

Why not:

d3.csv("../hello.csv", function(data) {
    console.log(data);
    var all = [];
    data.map(function (d) {
        Array.prototype.push.apply(all, d.description.split(" "));
    });
    console.log(all);
});

answered Jun 7, 2016 at 16:03

Ezequiel Muns

7,78035 silver badges59 bronze badges

2 Comments

njfife Over a year ago

This is exactly the suggestion I would give, make sure you mark this as the correct answer if it solved your problem. =)

Ezequiel Muns Over a year ago

@Jans: Great to hear, you can accept my answer if indeed it helped you :)

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