Hash select() and select!() methods in Ruby

In Ruby, we make use of the select() method when we want to find the array from the hash based on the condition and we make use of the select!() method when we want to check whether the array from the hash is present or not.

Let's explore a few examples of the hash select() method to understand it better.

Example 1

# Hash.select() method

# Hash value
first = { "first" => 150, "second" => 200 }

# Hash value
second = {"first" => 150}

# Hash value
third = {"first" => 150, "third" => 300, "second" => 200}

# select! Value
puts "A select present in Hash!: #{first.select {|key,value| key < "second"}}

"

Output

A select present in Hash!: {"first"=>150}

Example 2

# Hash.select() method

# declaring Hash value
second = {"first" => 150}

# declaring Hash value
third = {"first" => 150, "third" => 300, "second" => 200}

# select Value
puts "second select form : #{second.select{|key, value|value < 200}}

"

puts "third select form : #{third.select{|key, value|key < "second"}}

"

Output

second select form : {"first"=>150}
third select form : {"first"=>150}

Now let's see some examples of the hash select!() method in Ruby.

Example 3

# Hash.select!() method

# Hash value
first = { "first" => 150, "second" => 200 }

# Hash value
second = {"first" => 150}

# Hash value
third = {"first" => 150, "third" => 300, "second" => 200}

# select! Value
puts "A select present in Hash!: #{first.select! {|key, value| key < "second"}}

"

Output

A select present in Hash!: {"first"=>150}

Example 4

# Hash.select!() method

# declaring Hash value
second = {"first" => 150}

# declaring Hash value
third = {"first" => 150, "third" => 300, "second" => 200}

# select Value
puts "second select form : #{second.select!{|key, value| value < 200}}

"

puts "third select form : #{third.select!{|key, value| key < "second"}}

"

Output

second select form :
third select form : {"first"=>150}