How to Iterate Over a Map of Maps in Ruby - Step by Step Examples

How to Iterate Over a Map of Maps in Ruby ?

Answer

To iterate over a map of maps in Ruby, you can use nested loops. The outer loop iterates over the outer hash, and the inner loop iterates over the inner hash.

✐ Examples

1 Iterating Over a Map of Maps with Integer Keys and Values

We can iterate over a map of maps in Ruby where both the outer and inner hashes use integers for keys and values. This example demonstrates using nested loops to print each key-value pair.

For example,

We start by declaring and initializing a hash of hashes named outer_hash.
We use a nested loop to iterate over the outer and inner hashes and print each key-value pair.

Ruby Program

outer_hash = {
  1 => {1 => 10, 2 => 20, 3 => 30},
  2 => {4 => 40, 5 => 50, 6 => 60}
}

# Iterate over the hash of hashes
puts 'Iterating over hash of hashes with integer keys and values:'
outer_hash.each do |outer_key, inner_hash|
  puts "Outer key: #{outer_key}"
  inner_hash.each do |inner_key, value|
    puts "  Inner key: #{inner_key}, value: #{value}"
  end
end

Output

Iterating over hash of hashes with integer keys and values:
Outer key: 1
  Inner key: 1, value: 10
  Inner key: 2, value: 20
  Inner key: 3, value: 30
Outer key: 2
  Inner key: 4, value: 40
  Inner key: 5, value: 50
  Inner key: 6, value: 60

2 Iterating Over a Map of Maps with Mixed Key and Value Types

We can iterate over a map of maps in Ruby where the outer hash uses strings for keys and the inner hashes use integers for keys and strings for values. This example demonstrates using nested loops to print each key-value pair.

For example,

We start by declaring and initializing a hash of hashes named outer_hash with mixed key and value types.
We use a nested loop to iterate over the outer and inner hashes and print each key-value pair.

Ruby Program

outer_hash = {
  'first' => {1 => 'one', 2 => 'two', 3 => 'three'},
  'second' => {4 => 'four', 5 => 'five', 6 => 'six'}
}

# Iterate over the hash of hashes
puts 'Iterating over hash of hashes with mixed key and value types:'
outer_hash.each do |outer_key, inner_hash|
  puts "Outer key: #{outer_key}"
  inner_hash.each do |inner_key, value|
    puts "  Inner key: #{inner_key}, value: #{value}"
  end
end

Output

Iterating over hash of hashes with mixed key and value types:
Outer key: first
  Inner key: 1, value: one
  Inner key: 2, value: two
  Inner key: 3, value: three
Outer key: second
  Inner key: 4, value: four
  Inner key: 5, value: five
  Inner key: 6, value: six

3 Iterating Over a Map of Maps with String Keys and Double Values

We can iterate over a map of maps in Ruby where both the outer and inner hashes use strings for keys and floats for values. This example demonstrates using nested loops to print each key-value pair.

For example,

We start by declaring and initializing a hash of hashes named outer_hash with strings for keys and floats for values.
We use a nested loop to iterate over the outer and inner hashes and print each key-value pair.

Ruby Program

outer_hash = {
  'group1' => {'A' => 1.1, 'B' => 2.2, 'C' => 3.3},
  'group2' => {'D' => 4.4, 'E' => 5.5, 'F' => 6.6}
}

# Iterate over the hash of hashes
puts 'Iterating over hash of hashes with string keys and float values:'
outer_hash.each do |outer_key, inner_hash|
  puts "Outer key: #{outer_key}"
  inner_hash.each do |inner_key, value|
    puts "  Inner key: #{inner_key}, value: #{value}"
  end
end

Output

Iterating over hash of hashes with string keys and float values:
Outer key: group1
  Inner key: A, value: 1.1
  Inner key: B, value: 2.2
  Inner key: C, value: 3.3
Outer key: group2
  Inner key: D, value: 4.4
  Inner key: E, value: 5.5
  Inner key: F, value: 6.6

Summary

In this tutorial, we learned How to Iterate Over a Map of Maps in Ruby language with well detailed examples.

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How to Iterate Over a Map of Maps in Ruby - Step by Step Examples