Hashes
What are hashes?
- Like an array, but the index can be anything:
- integers, strings, symbols, or even objects
- Instead of array[1] = "fun" we have hash["ruby"] = "fun"
- Example:
- StudentNumbers = { "WDI4" => 9, "WDI5" => 15 }
An analogy
Array
Hash
Grocery shopping
Creating hashes:
code-along
Why are they cool?
- Human readable: animals[1] vs animals["cats"]
- One of the most common data structures you'll encounter
- Key-value logic is everywhere, even in NoSQL databases
When will you use them?
- Does your data need a label?
- Do you need fast lookups?
- Are you working with JSON?
- require 'json' then hash.to_json
Using hashes:
code-along
Further reading
