How to map/collect with index in Ruby?
Mapping or collecting elements with their corresponding indices in Ruby is a common requirement in various programming scenarios. Ruby provides several options to suit your needs.
Let’s explore four approaches to map or collect elements with their indices:
Table of Content
- Approach 1: Using each_with_index
- Approach 2: Using map.with_index
- Approach 3: Using Enumerable#each_with_index
- Approach 4: Using Range#each_with_index
Approach 1: Using each_with_index
Below is the Code:
array = ["a", "b", "c"]
array.each_with_index do |element, index|
puts "Element: #{element}, Index: #{index}"
end
Output
Element: a, Index: 0 Element: b, Index: 1 Element: c, Index: 2
Explanation:
- The
each_with_index
method iterates over each element in the array, providing both the element and its index to the block. - Within the block, you can perform any desired action using the element and index.
Approach 2: Using map.with_index
Below is the Code:
array = ["a", "b", "c"]
mapped_array = array.map.with_index do |element, index|
"Mapped Element #{index}: #{element}"
end
puts mapped_array
Output
Mapped Element 0: a Mapped Element 1: b Mapped Element 2: c
Explanation:
- The
map.with_index
method chains themap
method with thewith_index
method, allowing you to map elements along with their corresponding indices. - Within the block, you can perform any desired mapping operation using the element and index.
Approach 3: Using Enumerable#each_with_index
Below is the Code:
array = ["a", "b", "c"]
array.enum_for(:each_with_index).map do |element, index|
puts "Element: #{element}, Index: #{index}"
end
Output
Element: a, Index: 0 Element: b, Index: 1 Element: c, Index: 2
Explanation:
- You can use
enum_for(:each_with_index)
to create an enumerator and then chainmap
to perform operations similar toeach_with_index
. - This approach allows you to handle cases where
each_with_index
is not directly applicable.
Approach 4: Using Range#each_with_index
Below is the Code:
array = ["a", "b", "c"]
(0...array.length).each do |index|
puts "Element: #{array[index]}, Index: #{index}"
end
Output
Element: a, Index: 0 Element: b, Index: 1 Element: c, Index: 2
Explanation:
- This approach uses a range to iterate over indices and access elements within the array based on those indices.
- It’s useful when you want to avoid directly iterating over array elements.
Conclusion
Mapping or collecting elements with their corresponding indices in Ruby provides flexibility and enhances the capability of handling data structures effectively.
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