Change value of array element which is being referenced in a .each loop?

Question

How do I get the following to happen: I want to change the value of an array element which is being referenced between pipe characters in a .each loop.

Answer 1

Map is probably the best way, but you can change the string in-place too.

> a = "hello"
> puts a
=> hello

> a.replace("hi")
> puts a
=> hi

changes the internal value of the string. For example, your code could become :

x = %w(hello there world)
x.each { |e| if (e == "hello"); e.replace("hi") end; }

but this is much nicer :

x = %w(hello there world)
x.map! { |e| e == "hello" ? "hi" : e }

Answer 2

x = %w(hello there world)
x[index] = "hi" if index = x.index("hello")
x[index] = "hi" if index

or

x = %w(hello there world)
index = x.index("hello") and x[index] = "hi"

But one notice: it will replace only first match. Otherwise use map! as @SirDarlus suggested

Also you can use each_with_index

x.each_with_index do |element, index|
  x[index] = "hi" if element == "hello" # or x[index].replace("hi") if element == "hello"
end

But I still prefer using map! :)

Answer 3

You can get the result you want using collect! or map! to modify the array in-place:

x = %w(hello there world)
x.collect! { |element|
  (element == "hello") ? "hi" : element
}
puts x

At each iteration, the element is replaced into the array by the value returned by the block.

Answer 4

How about simply:

x = %w(hello there world).map! { |e| e == "hello" ? "hi" : e }

Answer 5

This is a way has less lines of code:

  x = %w(hello there world)
  x = x.join(",").gsub("hello","hi").split(",")
  puts x

Answer 6

The each method never changes the object it works on.

You should use map! method instead:

x = %w(hello there world)
x.map! { |element|
   if(element == "hello")
       "hi" # change "hello" to "hi"
   else
       element
   end
}
puts x # output: [hi there world]