How to Filter a Map Based on Values in Ruby - Step by Step Examples

How to Filter a Map Based on Values in Ruby ?

Answer

To filter a hash based on values in Ruby, you can use the `select` method to create a new hash containing only the key-value pairs that meet the filter criteria. This method allows you to create a subset of the original hash based on specific value conditions.

✐ Examples

1 Filtering a Hash Based on Value Range

We can filter a hash based on a range of values in Ruby by using the `select` method to create a new hash containing only the key-value pairs that fall within the specified range.

For example,

We start by declaring and initializing a hash named my_hash with some key-value pairs. In this example, the hash has integer keys and integer values.
We define the lower and upper bounds of the value range.
We use the select method to filter the hash based on the specified value range.
We print the filtered hash to the console using the puts function to verify the filtering.

Ruby Program

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

# Define the value range
lower_bound = 20
upper_bound = 40

# Filter the hash based on the value range
filtered_hash = my_hash.select { |_, v| v >= lower_bound && v <= upper_bound }

# Print the filtered hash
puts 'Filtered Hash by Value Range:'
filtered_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Filtered Hash by Value Range:
2: 20
3: 30
4: 40

2 Filtering a Hash Based on Specific Values

We can filter a hash based on specific values in Ruby by using the `select` method to create a new hash containing only the key-value pairs that match the specified values.

For example,

We start by declaring and initializing a hash named my_hash with some key-value pairs. In this example, the hash has integer keys and integer values.
We define a set of specific values that we want to filter the hash by.
We use the select method to filter the hash based on the specified values.
We print the filtered hash to the console using the puts function to verify the filtering.

Ruby Program

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

# Define the specific values to filter by
values_to_filter = [10, 30, 50]

# Filter the hash based on the specific values
filtered_hash = my_hash.select { |_, v| values_to_filter.include?(v) }

# Print the filtered hash
puts 'Filtered Hash by Specific Values:'
filtered_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Filtered Hash by Specific Values:
1: 10
3: 30
5: 50

3 Filtering a Hash with String Values Based on Prefix

We can filter a hash with string values based on a specific prefix in Ruby by using the `select` method to create a new hash containing only the key-value pairs that have values starting with the given prefix.

For example,

We start by declaring and initializing a hash named my_hash with some key-value pairs. In this example, the hash has integer keys and string values.
We define a prefix string that we want to filter the hash by.
We use the select method to filter the hash based on the specified prefix.
We print the filtered hash to the console using the puts function to verify the filtering.

Ruby Program

my_hash = { 1 => 'apple', 2 => 'banana', 3 => 'apricot', 4 => 'carrot', 5 => 'blueberry' }

# Define the prefix to filter by
prefix = 'ap'

# Filter the hash based on the prefix
filtered_hash = my_hash.select { |_, v| v.start_with?(prefix) }

# Print the filtered hash
puts 'Filtered Hash by Prefix:'
filtered_hash.each { |key, value| puts "#{key}: #{value}" }

Output

Filtered Hash by Prefix:
1: apple
3: apricot

Summary

In this tutorial, we learned How to Filter a Map Based on Values in Ruby language with well detailed examples.

◀ Previous Next ▶

Ruby Tutorials

Ruby How-Tos

How to Filter a Map Based on Values in Ruby - Step by Step Examples