From: Robert Klemme <shortcutter@...>
Date: 2008-04-25T06:20:04+09:00
Subject: Re: Question about array.each{|x| delete x}

On 24.04.2008 11:56, Peņa wrote:
> From: Frisco Del Rosario [mailto:frisco@appleisp.netNO] 
> # "why isn't it 1 2 3 one three 1 3?". 
> 
> a delete (of some element) on an array will really be deleted, ergo, the elements will rearrange/move to logically occupy that deleted space.
> 
> eg,
> b=[1,2,3,4,5]
> #=> [1, 2, 3, 4, 5]
> b.delete 2
> #=> 2
> b
> #=> [1, 3, 4, 5]
> 
> also, array#delete(obj) will delete all elements eql to obj. see below. 
> now, if you combine these behaviours while walking the array itself, expect some surprises if you're not ready :)
> 
> maybe if you show the index, ruby can help you, eg
> 
> a=[1,2,3,1,1,4]
> #=> [1, 2, 3, 1, 1, 4]
> a.each_with_index{|x,i| a.delete x if x==1; puts "#{i} -> #{x}"}
> 0 -> 1
> 1 -> 3
> 2 -> 4
> #=> [2, 3, 4]
> 
> 
> # What if I wanted to make it so?
> 
> there are many better ways, but i will just modify your sample,
> 
> myArray = [1, 2, 3]
> puts myArray
> myArray.delete 2  #here i delete 2 first
> myArray.each {|x|
>   if x == 1
>     then puts "one"
>   elsif x == 3
>     then puts "three"
>   end
> }
> puts myArray
> 
> 1
> 2
> 3
> one
> three
> 1
> 3
> 
> kind regards -botp
> 

Well, you can as well do

myArray = [1, 2, 3]

puts myArray

myArray.delete_if {|x|
   if x == 1 then
     puts "one"
   elsif x == 2 then
     true
   elsif x == 3 then
     puts "three"
   end
}

puts myArray

Note, this works because puts returns nil. :-)

But I'd prefer using case

myArray.delete_if do |x|
   case x
   when 1
     puts "one"
   when 2
     true
   when 3
     puts "three"
   end
end

Cheers

	robert