Forum: Ruby Iterate through array and delete if match

Announcement (2017-05-07): www.ruby-forum.com is now read-only since I unfortunately do not have the time to support and maintain the forum any more. Please see rubyonrails.org/community and ruby-lang.org/en/community for other Rails- und Ruby-related community platforms.
Jackster T. (Guest)
on 2008-10-04 04:11
I'm trying to delete elements of an array if they match a string but my
code always leaves some matches and I think it's because it's having
trouble iterating through the same array it is trying to delete from, is
that true?

Here is the code:

@acl_all_array.each do |range|
     if range[/access-list/]
       @acl_all_array.delete(range)
       puts range
     end
  end

Is this the correct way to delete matched entries from an array?

Thanks

John
Tim H. (Guest)
on 2008-10-04 04:20
(Received via mailing list)
jackster the jackle wrote:
>        puts range
>      end
>   end
>
> Is this the correct way to delete matched entries from an array?
>
> Thanks
>
> John

Use delete_if instead.
Ragav S. (Guest)
on 2008-10-04 04:43
Tim H. wrote:
> jackster the jackle wrote:
>>        puts range
>>      end
>>   end
>>
>> Is this the correct way to delete matched entries from an array?
>>
>> Thanks
>>
>> John
>
> Use delete_if instead.

Or Array#reject!

deleting while iterating with each is undefined behavior. It's like
sawing off the tree branch you are sitting on.
Jackster T. (Guest)
on 2008-10-04 05:02
> Or Array#reject!
>
> deleting while iterating with each is undefined behavior. It's like
> sawing off the tree branch you are sitting on.


hehehe...I know what you mean!

Tim's solution worked, I used:

@acl_all_array.each do |range|
     if range[/access-list/]
       @acl_range.push(range)
     end
  end
@acl_all_array.delete_if { |x| x[/access-list/] }

Thanks for all the help guys...I am going to read up on Array#reject! to
see how that might help me.

john
Shawn A. (Guest)
on 2008-10-04 05:08
(Received via mailing list)
I believe there is a method on Array called delete_if for just such a
case..
IIRC

/Shawn
David A. Black (Guest)
on 2008-10-04 07:40
(Received via mailing list)
Hi --

On Sat, 4 Oct 2008, jackster the jackle wrote:

> @acl_all_array.each do |range|
>     if range[/access-list/]
>       @acl_range.push(range)
>     end
>  end
> @acl_all_array.delete_if { |x| x[/access-list/] }
>
> Thanks for all the help guys...I am going to read up on Array#reject! to
> see how that might help me.

Check out Array#partition too. What you've got there looks like it
could be:

   @acl_all_array, @acl_range = @acl_all_array.partition do |range|
     range[/access-list/]
   end

or something like that.


David
Jackster T. (Guest)
on 2008-10-04 14:27
David A. Black wrote:
> Hi --
>
> Check out Array#partition too. What you've got there looks like it
> could be:
>
>    @acl_all_array, @acl_range = @acl_all_array.partition do |range|
>      range[/access-list/]
>    end
>
> or something like that.


good call David.....I'm going to try and incorporate that into my code.
Nice to see you on the forum! I'm still mad that my training was never
approved :-(

john
Robert K. (Guest)
on 2008-10-05 20:26
(Received via mailing list)
On 04.10.2008 12:26, jackster the jackle wrote:
>> or something like that.
And, to give you another option you can fill the second array inside the
delete_if block as well:

@acl_all_array.delete_if { |x| x[/access-list/] and
   @acl_range.push(x)}

Cheers

  robert
This topic is locked and can not be replied to.