Asp Forum - Array#find! - comp.lang.ruby

Trans

3/1/2008 12:45:00 AM

How to remove the first occurrence of something?

a=[1,2,3,4]
a.find!{ |e| a==2 } #=> 2

But there is no #find!, how to define it? My solutions seem unduly
complex.

Thanks,
T.

5 Answers

7stud --

3/1/2008 1:15:00 AM

Trans wrote:
> How to remove the first occurrence of something?
>
> a=[1,2,3,4]
> a.find!{ |e| a==2 } #=> 2
>
> But there is no #find!, how to define it? My solutions seem unduly
> complex.
>
> Thanks,
> T.

More complex than the following?

arr = [1, 2, 3, 2, 2, 2]

arr.each_with_index do |elmt, i|
if elmt == 2
arr.delete_at(i)
break
end
end

p arr

[1, 3, 2, 2, 2]

--
Posted via http://www.ruby-....

Christopher Swasey

3/1/2008 1:26:00 AM

On 2/29/08, 7stud -- <bbxx789_05ss@yahoo.com> wrote:
> Trans wrote:
> > How to remove the first occurrence of something?
> >
> > a=[1,2,3,4]
> > a.find!{ |e| a==2 } #=> 2
> >
> > But there is no #find!, how to define it? My solutions seem unduly
> > complex.
> >
> > Thanks,
> > T.
>
>
> More complex than the following?
>
> arr = [1, 2, 3, 2, 2, 2]
>
> arr.each_with_index do |elmt, i|
> if elmt == 2
> arr.delete_at(i)
> break
> end
> end

Why not just...
arr = [1, 2, 2, 2, 3]
arr.delete_at(arr.index(2))

arr => [1, 2, 2, 3]

Christopher

Joel VanderWerf

3/1/2008 1:30:00 AM

7stud -- wrote:
> arr.each_with_index do |elmt, i|
> if elmt == 2
> arr.delete_at(i)
> break
> end
> end

If you're going that far, why not just

arr.delete_at(arr.index(2))

(Of course that's limited to #== comparisons. Maybe Array#index should
take a block...)

--
vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

Andre Nathan

3/1/2008 2:11:00 AM

On Sat, 2008-03-01 at 10:15 +0900, 7stud -- wrote:
> arr.each_with_index do |elmt, i|
> if elmt == 2
> arr.delete_at(i)
> break
> end
> end

This won't work in 1.9: "RuntimeError: can't modify array during
iteration".

Best,
Andre

Peña, Botp

3/1/2008 2:21:00 AM

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