How to Sort a Map by Keys in Ruby - Step by Step Examples

How to Sort a Map by Keys in Ruby ?

Answer

To sort a hash by keys in Ruby, you can use the `sort.to_h` method, which returns a new hash with the keys sorted. This method provides a straightforward way to ensure the hash is sorted by keys.

✐ Examples

1 Sorting a Hash by Keys Using sort.to_h

We can sort a hash by keys in Ruby by using the `sort.to_h` method, which returns a new hash with the keys sorted.

For example,

We start by declaring and initializing a hash named unsorted_hash with some key-value pairs. In this example, the hash has string keys and integer values.
We use the sort.to_h method to create a new hash named sorted_hash that contains the same key-value pairs but with sorted keys.
We print the sorted hash to the console using the puts function to verify the sorting.

Ruby Program

unsorted_hash = { 'c' => 3, 'a' => 1, 'b' => 2 }

# Sort the hash by keys
sorted_hash = unsorted_hash.sort.to_h

# Print the sorted hash
puts 'Sorted Hash by Keys:'
sorted_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Sorted Hash by Keys:
a: 1
b: 2
c: 3

2 Sorting a Hash by Keys in Descending Order

We can sort a hash by keys in descending order in Ruby by using the `sort_by.to_h` method with a custom comparator.

For example,

We start by declaring and initializing a hash named unsorted_hash with some key-value pairs. In this example, the hash has string keys and integer values.
We use the sort_by.to_h method with a custom comparator to create a new hash named sorted_hash that contains the same key-value pairs but with keys sorted in descending order.
We print the sorted hash to the console using the puts function to verify the sorting.

Ruby Program

unsorted_hash = { 'c' => 3, 'a' => 1, 'b' => 2 }

# Sort the hash by keys in descending order
sorted_hash = unsorted_hash.sort_by { |k, _v| -k.ord }.to_h

# Print the sorted hash
puts 'Sorted Hash by Keys (Descending):'
sorted_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Sorted Hash by Keys (Descending):
c: 3
b: 2
a: 1

3 Sorting a Hash with Numeric Keys

We can sort a hash with numeric keys in Ruby by using the `sort.to_h` method, which returns a new hash with the keys sorted numerically.

For example,

We start by declaring and initializing a hash named unsorted_hash with some key-value pairs. In this example, the hash has integer keys and string values.
We use the sort.to_h method to create a new hash named sorted_hash that contains the same key-value pairs but with keys sorted numerically.
We print the sorted hash to the console using the puts function to verify the sorting.

Ruby Program

unsorted_hash = { 3 => 'three', 1 => 'one', 2 => 'two' }

# Sort the hash by numeric keys
sorted_hash = unsorted_hash.sort.to_h

# Print the sorted hash
puts 'Sorted Hash by Keys:'
sorted_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Sorted Hash by Keys:
1: one
2: two
3: three

Summary

In this tutorial, we learned How to Sort a Map by Keys in Ruby language with well detailed examples.

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