From: "David A. Black" <dblack@...>
Date: 2009-04-27T19:19:18+09:00
Subject: Re: Deleting numbers in array

Hi --

7stud -- wrote:
> 7stud -- wrote:
>> Clayton Lane wrote:
>>> David A. Black wrote:
>>>> Hi --
>>>>
>>>> Clayton Lane wrote:
>>>>> I'm new to Ruby and unsure how to delete numbers in an array. I have an
>>>>> array filled with numbers from 1 to 100. If I use nums.delete_if {|x| x
>>>>> == 9 }, it will delete 9, but I want to remove any number containing 9.
>>>>> For example, 19, 39, 92, 99 etc. I tried using a wildcard, but it didn't
>>>>> work. I'm sure theres an easy command to do it, but I wasn't able to
>>>>> find it on in Ruby documentation. I also want to remove numbers
>>>>> containing 0,6,7, and 8 as well. Any help would be greatly appreciated.
>>>> You're pretty much going to have to convert the numbers to strings. For
>>>> example:
>>>>
>>>>     array.delete_if {|x| x.to_s[/[06789]/] }
>>>>
>>>>
>>>> David
>>> Wow! Ruby is so good! I'm unsure of how to do this final step too. If
>>> any numbers don't contain 1, remove them. Any ideas?
>> arr = [51, 52, 20, 36, 79]
>> result = arr.delete_if {|x| x.to_s[/[06789]/]}
>> p result
>>
>> --output:--
>> [51, 52]
>>
>> result = arr.delete_if do |x|
>>    str = x.to_s
>>    str[/[02345]/] and not str[/1/]
>> end
>> p result
>>
>> --output:--
>> [51]
>
> lol.  I screwed that up!  I guess it was easier for me in C++ than ruby.
> Hmm...for a ruby solution, I find that I have to use the same structure
> as the C++ program:
>
> arr = [51, 52, 22, 20, 36, 79]
> result = arr.delete_if {|x| x.to_s[/[06789]/]}
> p result
>
> result = arr.delete_if do |x|
>    str = x.to_s
>
>    if str[/06789/]
>      true #delete
>    elsif not str[/1/]
>      true #delete
>    else
>      false #keep
>    end
>
> end
> p result
>
> --output:--
> [51, 52, 22]
> [51]

You're working much too hard :-) I'm not sure whether the OP only cares 
about the 1's, or wants to do both tests, but assuming the latter:

   arr.delete_if {|x| s = x.to_s; s[/[06789]/] ||! s[/1/] }


David

-- 
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