How to define array of hash objects in ruby?

Question

There are plenty of answers that allow us to achieve this like so:

array = [a: 1, b: 2, c: 3]. But what I'm looking for is something more closer to c++ or java implementation.

In C++ we can define an array of pairs like so:

map <pair<int,int>,int> mp;

and perhaps use it for assigning values like:

mp[{x1,y1}] = 1;

Or to check if some element exist like so:

while(range(x,y) && !mp[{x,y}]) {
    x += xx;
    y += yy;
    ans++;
 }

Now the question is, how can we define our array of hashes similar to c++ where we have something like:

 array = [{1,1}: 1, {2,2}: 2, {3,3}: 3]

Your last line says what you want, but it's not clear what you are given to produce that. Is it a = [1,2,3]? Please edit to clarify. — Cary Swoveland
– Cary Swoveland, Commented Oct 27, 2018 at 18:41
{1,1} is not a valid Ruby object. Do you mean the array[1,1]? — Cary Swoveland
– Cary Swoveland, Commented Oct 27, 2018 at 18:46

Cary Swoveland · Accepted Answer · 2018-10-27 18:53:09Z

3

a = [1, 2, 3]

a.map { |e| { [e,e] => e } }
  #=> [{[1, 1]=>1}, {[2, 2]=>2}, {[3, 3]=>3}]

edited Oct 27, 2018 at 18:53

answered Oct 27, 2018 at 18:44

Cary Swoveland

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Ilya Konyukhov · Accepted Answer · 2018-10-27 18:49:07Z

2

In Ruby maps are called Hashes. A Hash is a dictionary-like collection of unique keys and their values. The key of the hash can be of any type: number, symbol, string, array, other hash, etc.

So you could write it as a hash, where keys are arrays:

hash = {[1, 1] => 1, [2, 2] => 2, [3, 3] => 3}
# => {[1, 1]=>1, [2, 2]=>2, [3, 3]=>3} 

hash[[2, 2]]
# => 2

hash[[12, 34]] = 55
# => 55 

hash
# => {[1, 1]=>1, [2, 2]=>2, [3, 3]=>3, [12, 34]=>55}

edited Oct 27, 2018 at 18:49

answered Oct 27, 2018 at 18:43

Ilya Konyukhov

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