Converting array to hash (Ruby)

Question

Below is the question in my class.

Given the variable some_array = [[:a, 123], [:b, 456]],
convert some_array into this hash: {a: 123, b: 456}

Possible duplicate of [What is the best way to convert an array to a hash in Ruby](http://stackoverflow.com/questions/39567/what-is-the-best-way-to-convert-an-array-to-a-hash-in-ruby) — Sagar Pandya, Jan 24 '17 at 18:17
Please read "[ask]" including the linked pages, "[mcve]" if you have a problem with code you wrote, and http://meta.stackoverflow.com/q/261592/128421 — the Tin Man, Jan 24 '17 at 18:17
Since this is a question from a class, do you think you will learn if you have others tell you how to do it? Instead, you need to dig in and try to find it yourself. When asking a question like this, it's especially important to show us your effort. That lets us know you've tried. — the Tin Man, Jan 24 '17 at 18:20

Umar Ghouse · Accepted Answer · 2017-01-24T18:34:53.003

4

I'm a beginner too, so this may be a little inefficient, but this is how I would explain it (there are simpler methods I'm sure, but since you mentioned this is for a class, I thought I'd explain in long form):

hash={}

some_array.each do |item|
    hash[item[0]] = item[1]
end

Just to explain that a bit, I start by creating an empty hash that I will use later.

Then I cycle through some_array using the each method. This assigns each element in some_array to the variable item. Given that some_array is a nested array (which basically means that it is an array of arrays), the item variable will take the value of the inner arrays - for example, item = [:a, 123].

Then we can access each element within item when creating the hash. Following the same example I gave earlier item[0] == :a and item[1] == 123.

Then I use some shorthand when creating hashes - i.e. hash[key] = value. In this case, I want the key to be :a (which is item[0]) and the value to be 123 (which is item[1]). So I can use hash[item[0]] = item[1].

Hope that helped!

edited Jan 24 '17 at 18:34

answered Jan 24 '17 at 18:31

Umar Ghouse

398
3
19

Why would you do it that way when the `.to_h` method does exactly this? While it can be educational to implement things like this for academic reasons, the solution is to read the manual and look for what tools are available. – tadman Jan 24 '17 at 18:32
Thank you @tadman , since it seems like a basic problem, I figured he must have just started out and would appreciate the explanation. But your comment is valid too, using the tools available is just as important. – Umar Ghouse Jan 24 '17 at 18:38
I'm not trying to slag you here, just saying that in production code you should do it by the book. As always, yearn to understand more and do experiment. For example, your code can be improved by using [`each_with_object`](http://ruby-doc.org/core-2.4.0/Enumerable.html#method-i-each_with_object) if you want to use that approach. Sometimes what you're doing is valid because you want to perform conversion on each `item[1]`. – tadman Jan 24 '17 at 18:48

score 1 · Answer 2 · answered Jan 24 '17 at 18:43

1

To convert in to hash simply use .to_h method

some_array.to_h

answered Jan 24 '17 at 18:43

Hardik Gondaliya

316
3
12

Converting array to hash (Ruby)

2 Answers2