map each with index
Ruby's map
method, when used with the with_index
method, allows you to iterate over an array and access both the elements and their respective indices. Here's a step-by-step explanation of how it works:
Start with an array: Let's say we have an array called
my_array
with some elements:[10, 20, 30, 40, 50]
.Use the
map
method: Call themap
method on the array and provide a block to define the transformation to be applied to each element. For example, we can square each element by writingmy_array.map { |element| element 2 }
.Add the
with_index
method: In order to access the index of each element, we chain thewith_index
method after themap
method. This method takes an optional argument to specify the starting index. For example,my_array.map.with_index(1) { |element, index| ... }
would start the index from 1 instead of the default 0.Access each element and index: Within the block, you can now access each element using the
element
variable and the index using theindex
variable. For example,my_array.map.with_index { |element, index| puts "Element #{element} is at index #{index}" }
.Return the transformed array: The
map
method automatically collects the return values of each iteration and returns them as a new array. So, if you want to collect the squared elements, you can assign the result of themap
method to a variable, likesquared_array = my_array.map { |element| element 2 }
.
That's it! By combining the map
method with the with_index
method, you can easily iterate over an array, access each element and its index, and perform transformations or collect the results.