Reputation: 1321

Delete an element from an Array based on a condition block and return that element

Is there a quick Ruby or Rails method to delete an element from an Array based on a condition provided in a block and then return that element?

Let's say, given:

e1.good? # false
e2.good? # true
e3.good? # true
a = [e1, e2, e3]

Is there a method delete_and_return_if doing this:

a.delete_and_return_if { |e| e.good? }      # delete e2 from a and returns e2
[e1].delete_and_return_if { |e| e.good? }   # returns nil

Or at least is there a clean way to do this?

Upvotes: 1

Answers (4)

Reputation:

This will update array and return deleted entry:

a = [1, 2, 3]

p a
# => [1, 2, 3]

deleted = a.delete a.detect {|e| e == 2 }
p deleted
# => 2

p a
# => [1, 3]

so you can do like this:

a.delete a.detect(&:good?)

UPDATE: thanks to @oldergod for recalling me about detect

Upvotes: 1

Reputation: 15010

If you do not have duplicates or that you want to delete all same elements, you can do

a.delete(a.detect(&:good?))

a.detect(&:good?) will return the first good? object or nil if there is none.
a.delete(elem) will delete and return your element.

Or if you have duplicates and only want to delete the first one:

a.delete(a.index(a.detect(&:good?)))

Upvotes: 1

Reputation: 1815

 a = [e1, e2, e3]

 a.delete_if{|e|!e.good?}

 it will delete e1. and returns e2 and e3

Upvotes: 1

Reputation: 1988

Upvotes: 1