How to group and transform dictionary array on a certain key attribute to a different format with javascript (functional programming)?

Question

I'd like to transform the below dataset array into a different format. Currently, each dictionary in the array has a 'count', 'fruit', and 'first name'. I'd like to create a new dictionary for each distinct first name and values that first name has for each 'fruit' type.

For example, see below for some input data

var input_data = [{"count":1,"fruit":"apple","first_name":"abe"},{"count":1,"fruit":"apple","first_name":"bob"},{"count":10,"fruit":"banana","first_name":"bob"},{"count":5,"fruit":"cherry","first_name":"abe"}]

We know for this dataset that the categories are ['apple', 'banana', 'cherry']

var desired_output = 
[{name: 'abe',data:[1,0,5]},
{name: 'bob',data:[1,10,0]}]

I don't see any relation between input_data and data arrays in the desired output? — Ozan
– Ozan, Commented Aug 8, 2016 at 17:40
@Bergi - How do you use groupBy? That might be what I'm looking for. — Chris
– Chris, Commented Aug 8, 2016 at 21:36
@Ozan - the relation is essentially that I want one dictionary for abe and one dictionary for bob, where there is an attribute called 'data' that has a list indicating how many of each fruit he has. So for example, we know Bob above has 1 Apple, 10 Bananas, and 0 Cherries based on the input, so I want the list to be [1,10,0]. — Chris
– Chris, Commented Aug 8, 2016 at 21:40
@Chris: First, make the categories array from a simple iteration (or something like uniq(map('fruit', data))). Use groupBy with the .first_name property, then map the values to the desired output elements (selecting the name, mapping every item to its index in the categories array). — Bergi
– Bergi, Commented Aug 8, 2016 at 22:02

Nina Scholz · Accepted Answer · 2016-08-08 21:44:13Z

1

You could use a hash table for the name reference and an object for the rigth index for counting.

var input_data = [{"count":1,"fruit":"apple","first_name":"abe"},{"count":1,"fruit":"apple","first_name":"bob"},{"count":10,"fruit":"banana","first_name":"bob"},{"count":5,"fruit":"cherry","first_name":"abe"}],
    categories = ['apple', 'banana', 'cherry'],
    cat = {},
    result = [];

categories.forEach(function (a, i) { cat[a] = i; });
input_data.forEach(function (a) {
    if (!this[a.first_name]) {
        this[a.first_name] = { name: a.first_name, data: categories.map(function () { return 0; }) };
        result.push(this[a.first_name]);
    }
    this[a.first_name].data[cat[a.fruit]] += a.count;
}, Object.create(null));
console.log(result);

edited Aug 8, 2016 at 21:44

answered Aug 8, 2016 at 18:08

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Chris Over a year ago

The only issue here is that I'd like the result to reflect that Bob has 10 bananas and Abe has 5 cherries. For example, the result here generates [{name: 'abe',data:[1,0,1]}, {name: 'bob',data:[1,1,0]}], but I want it to generate [{name: 'abe',data:[1,0,5]}, {name: 'bob',data:[1,10,0]}]

Collectives™ on Stack Overflow

How to group and transform dictionary array on a certain key attribute to a different format with javascript (functional programming)?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related