Question

I’m still learning Ruby and I have a question concerning hash of hashes. The hash bellow is what I would like to access :

reserved_instance_price = [
                              'us-east-1' => ['t1.micro' => 0.02, 'm1.small' => 0.08, 'm1.medium' => 0.160 ],
                              'us-west-1' => ['t1.micro' => 0.02, 'm1.small' => 0.08, 'm1.medium' => 0.160 ],
                              'eu-west-1' => ['t1.micro' => 0.02, 'm1.small' => 0.085, 'm1.medium' => 0.170 ]
                            ]

My questions: Is it the right way to implement hashes of hashes in ruby ? and how to access a particular value ?

Thank you

Answer 1

[] syntax is for arrays. To construct hashes use {}

Your example becomes

reserved_instance_price = {
                              'us-east-1' => {'t1.micro' => 0.02, 'm1.small' => 0.08, 'm1.medium' => 0.160 }
}

For accessing a particular value simply do

reserved_instance_price['us-east-1']['t1.micro'] which will return 0.02

If you would like your indexes to be symbols rather than string, you can also use the syntax

h = { useast1: {t1micro: 0.02}}

Access becomes

h[:useast1][:t1micro]