Delete array elements from another array

Question

I got 2 arrays:

a = [1,2,3,4,5]
b = [4,5,6,7,8]

I want to delete every b element in a, in order for a to have [1,2,3]

Of course, my real arrays are different.

I want a beautiful answer with a simple method, since I can resolve this issue by using this loop, but I find it ugly.

b.each do |e|
  a.delete(e) if a.include?(e)
end
return a

It seems that reject may be the way to go, but couldn't find the good way. Thanks you

Arup Rakshit · Accepted Answer · 2014-03-31 13:58:09Z

6

Just do as below using Array Difference :-

a = [1,2,3,4,5]
b = [4,5,6,7,8]
a = a - b
a # => [1,2,3]

But I would suggest, don't modify the source array. Rather do

new_ary = a - b

answered Mar 31, 2014 at 13:58

Arup Rakshit

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2 Comments

Beautiful ! Thanks, Accepted; could you tell me how to use the reject method by the way please (is it possible to use it here) ?

@sidney You can use - a.reject { |e| b.include?(e) } .. But Array#- is perfect for this.