How to Make a Custom Array of Hashes in Ruby?
Prerequisites: Hashes and Arrays in Ruby
Arrays and hashes are data structures that allow you to store multiple values at once. In this article, we will explore their syntax, how to combine functionalities of both to create an array of hashes, retrieve values, and loop through them.
An array is a collection of different or similar items, stored at contiguous memory locations. The idea is to store multiple items of the same type together, which can be referred to by a common name.
Here is how an array is declared in Ruby:
arr = ["Beginner", 55, 61, "GFG"]
Hash is a data structure that maintains a set of objects which are termed as the keys and each key associates a value with it. In simple words, a hash is a collection of unique keys and their values.
Here is how an array is declared in Ruby:
hash_variable = { "key1" => "Beginner", "key2" => "for", "key2" => "Beginner" }
Creating an array of hashes
You are allowed to create an array of hashes either by simply initializing array with hashes or by using array.push() to push hashes inside the array.
A simple method to create an array of hashes:
hash_arr = [ {"height" => '5 ft', "weight" => '170 lbs', "hair" => 'white'}, {:pet => 'Cat', :nest => 'Bird'} ]
Or Using array.push() to push hashes inside the array:
hash_arr = [] hash1 = {"height" => '5 ft', "weight" => '170 lbs', "hair" => 'White'} hash2 = {:pet => 'Frog', :nest => 'Bird'} hash_arr.push(hash1) hash_arr.push(hash2)
Note: Both “Key” and :Key acts as a key in a hash in ruby.
Accessing an array of hashes
You can access the elements of an array of hashes by using array-based indexing to access a particular hash and keys to access values present in that hash.
hash_arr = [ {"height" => '5 ft', "weight" => '170 lbs', "hair" => 'white'}, {:pet => 'Cat', :nest => 'Bird'} ] hash_arr[0]["height"] #=> '5 ft' hash_arr[1][:nest] #=> 'Bird'
Example:
# Ruby program to illustrate how to access # the element of the array of hashes # Creating an array of hashes hash_arr = [ { "name" => 'w3wiki' , "branch" => 'CSE' }, { :language1 => 'Ruby' , :language2 => 'Python' } ] # Accessing the elements of hash_arr res1 = hash_arr[ 0 ][ "branch" ] res2 = hash_arr[ 1 ][ :language1 ] # Display the results puts res1 puts res2 |
Output:
CSE Ruby
Iterate over the array of hashes
You can use simple .each do statements to iterate over the array of hashes:
Example:
# Ruby program to illustrate how to access # the element of the array of hashes # Creating an array of hashes hash_arr = [ {name: 'Amu' , occupation: 'Web developer' , hobbies: 'Painting' }, {name: 'Sumit' , occupation: 'HR' , hobbies: 'Swimming' } ] # Iterate over the array of hashes # Using .each do statement hash_arr. each do |hash| puts 'Values in this Hash' hash. each do |key,value| puts (key.to_s + ': ' + value.to_s) end end |
Output:
Values in this Hash name: Amu occupation: Web developer hobbies: Painting Values in this Hash name: Sumit occupation: HR hobbies: Swimming
Note: .to_s is used to convert all values into strings so they can be easily printed.
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