How to Swap Keys and Values in a Map in Ruby

How to Swap Keys and Values in a Map in Ruby ?

Answer

To swap keys and values in a map in Ruby, you can iterate over the original hash and insert each key-value pair into a new hash with the value as the key and the key as the value. This method allows you to create a new hash with swapped key-value pairs.


✐ Examples

1 Swapping Keys and Values in a Hash of Integers

We can swap keys and values in a hash of integers in Ruby by iterating over the original hash and inserting each key-value pair into a new hash with the value as the key and the key as the value.

For example,

  1. We start by declaring and initializing a hash of integers named original_hash.
  2. We declare an empty hash named swapped_hash to store the swapped key-value pairs.
  3. We iterate over the original hash using the each method and insert each key-value pair into the new hash with the value as the key and the key as the value.
  4. We print the resulting hash to the console to verify the swap.

Ruby Program

original_hash = {
  1 => 10,
  2 => 20,
  3 => 30,
  4 => 40,
  5 => 50
}

# Declare an empty hash to store the swapped key-value pairs
swapped_hash = {}

# Iterate over the original hash and insert each key-value pair into the new hash with the value as the key and the key as the value
original_hash.each do |key, value|
  swapped_hash[value] = key
end

# Print the resulting hash
puts 'Swapped hash of integers:'
swapped_hash.each do |key, value|
  puts "#{key}: #{value}"
end

Output

Swapped hash of integers:
10: 1
20: 2
30: 3
40: 4
50: 5

2 Swapping Keys and Values in a Hash of Strings

We can swap keys and values in a hash of strings in Ruby by iterating over the original hash and inserting each key-value pair into a new hash with the value as the key and the key as the value.

For example,

  1. We start by declaring and initializing a hash of strings named original_hash.
  2. We declare an empty hash named swapped_hash to store the swapped key-value pairs.
  3. We iterate over the original hash using the each method and insert each key-value pair into the new hash with the value as the key and the key as the value.
  4. We print the resulting hash to the console to verify the swap.

Ruby Program

original_hash = {
  'one' => 'uno',
  'two' => 'dos',
  'three' => 'tres',
  'four' => 'cuatro',
  'five' => 'cinco'
}

# Declare an empty hash to store the swapped key-value pairs
swapped_hash = {}

# Iterate over the original hash and insert each key-value pair into the new hash with the value as the key and the key as the value
original_hash.each do |key, value|
  swapped_hash[value] = key
end

# Print the resulting hash
puts 'Swapped hash of strings:'
swapped_hash.each do |key, value|
  puts "#{key}: #{value}"
end

Output

Swapped hash of strings:
uno: one
dos: two
tres: three
cuatro: four
cinco: five

3 Swapping Keys and Values in a Hash of Mixed Types

We can swap keys and values in a hash with mixed key and value types in Ruby by iterating over the original hash and inserting each key-value pair into a new hash with the value as the key and the key as the value. This example demonstrates swapping keys of type Integer with values of type String.

For example,

  1. We start by declaring and initializing a hash with mixed types named original_hash.
  2. We declare an empty hash named swapped_hash to store the swapped key-value pairs.
  3. We iterate over the original hash using the each method and insert each key-value pair into the new hash with the value as the key and the key as the value.
  4. We print the resulting hash to the console to verify the swap.

Ruby Program

original_hash = {
  1 => 'one',
  2 => 'two',
  3 => 'three',
  4 => 'four',
  5 => 'five'
}

# Declare an empty hash to store the swapped key-value pairs
swapped_hash = {}

# Iterate over the original hash and insert each key-value pair into the new hash with the value as the key and the key as the value
original_hash.each do |key, value|
  swapped_hash[value] = key
end

# Print the resulting hash
puts 'Swapped hash of mixed types:'
swapped_hash.each do |key, value|
  puts "#{key}: #{value}"
end

Output

Swapped hash of mixed types:
one: 1
two: 2
three: 3
four: 4
five: 5

Summary

In this tutorial, we learned How to Swap Keys and Values in a Map in Ruby language with well detailed examples.


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  29. How to Convert an Array of Key-Value Pairs to a Map in Ruby ?
  30. How to Convert a Map to a JSON String in Ruby ?
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