Data structure to describe multiple boolean values as keys - ruby

Question

I have javascript weather classification app which I am porting to ruby.
The classifications are stored in a json as
"classification": [
{
"warm": false,
"sunny": false,
"windy": false,
"desc": "cold-drizzle"
},
{
"warm": false,
"sunny": false,
"windy": true,
"desc": "storm"
},
{
"warm": false,
"sunny": true,
"windy": false,
"desc": "winter-wonderland"
}, etc
There are with other words eight different classifications.
What would be a concise ruby way to describe this structure? Perhaps a hash with multiple booleans as key?

Answer 1

Hashes in Ruby can be indexed by anything, including other hashes. So:
classifications = {}
classifications[ {warm:false, sunny:false, windy:false} ] = "cold-drizzle"
classifications[ {warm:false, sunny:true, windy:false} ] = "winter-wonderland"
p classifications
#=> {
#=> {:warm=>false, :sunny=>false, :windy=>false}=>"cold-drizzle",
#=> {:warm=>false, :sunny=>true, :windy=>false}=>"winter-wonderland"
#=> }
p classifications[ {sunny:false, windy:false, warm:false } ]
#=> "cold-drizzle"
Note the arbitrary ordering I used for the hash keys when reading the value. You don't have to use the exact same hash object you used when writing (as you would with Lua), you simply need to use hash whose data is equivalent.
Due to the syntax sugar of Ruby's method calls, you can even leave off all the { and } in the above (except where the hash is declared):
classifications[ warm:false, sunny:false, windy:true ] = "stormy"
p classifications[ warm:false, sunny:false, windy:false ]
#=> "cold-drizzle"
If you want to be more terse but less descriptive, you can also just use arrays for your keys:
classifications = {}
classifications[ [false,false,false] ] = "cold-drizzle"
classifications[ [false,true, false] ] = "winter-wonderland"
p classifications[ [false,true,false] ]
#=> "winter-wonderland"
Note that—as with the hashes as keys—you do not need to use the exact same object to index the hash, just an object that is considered equal.

Answer 2

Exactly like the JSON (array of objects):
You could use the Struct class to replicate the objects in your JSON
classifications = []
Classification = Struct.new(:warm, :sunny, :windy, :desc)
classifications << Classification.new(false, false, false, "cold_drizzle")
You could also just have an array of hashes:
classifications = []
classifications << {warm: false, sunny: false, windy: false, desc: "cold_drizzle"}
Or, if you're looking for a hash with the three booleans as a key to the description:
You could use Struct again:
classifcations = {}
Classification = Struct.new(:warm, :sunny, :windy)
classifications[Classification.new(false, false, false)] = "cold_drizzle"
You could use plain integers:
classifications = {}
classifications[0] = "cold_drizzle"
classifications[1] = "storm"
You could use arrays:
classifications = {}
classifications[[false, false, false]] = "cold_drizzle"
Or anything else you like. This question is a little open-ended, but there are some ideas.

Answer 3

Use JSON#parse
Given a valid JSON string, you can just parse it into a valid Ruby hash with JSON#parse. For example:
require 'json'
json_string = <<EOF
{"classification": [{
"warm": false,
"sunny": false,
"windy": false,
"desc": "cold-drizzle"
}, {
"warm": false,
"sunny": false,
"windy": true,
"desc": "storm"
}, {
"warm": false,
"sunny": true,
"windy": false,
"desc": "winter-wonderland"
}]}
EOF
hash = JSON.parse(json_string)
You can then access your new Hash object with an assortment of methods. For example:
hash['classification'].first
#=> {"warm"=>false, "sunny"=>false, "windy"=>false, "desc"=>"cold-drizzle"}