strip out repeated ocurrence of a string

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Hello list :)

I have this problem, a certain string can contain the following information:


$string = '
hi{value1;value2}
bye{value1;value3}
hi{value1;value4}
hi{value1;value2}
bye{value1;value2}
';

What I want is to be able to get this result:

$string = '
hi{value1;value2}
bye{value1;value3}
hi{value1;value4}
bye{value1;value2}
';

(the order of appearance doesn't matter)
Is it even possible to do this with regular expresions? Or should I first
look if there is some kind of match and then apply an
str_replace($match,'',$string) and add the $match again?

Greetings !

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Re: strip out repeated ocurrence of a string

On 1/25/2010 10:48 PM, Camilo Sperberg wrote:
> Hello list :)
>
> I have this problem, a certain string can contain the following information:
>
>
> $string = '
> hi{value1;value2}
> bye{value1;value3}
> hi{value1;value4}
> hi{value1;value2}
> bye{value1;value2}
> ';
>
> What I want is to be able to get this result:
>
> $string = '
> hi{value1;value2}
> bye{value1;value3}
> hi{value1;value4}
> bye{value1;value2}
> ';
>
> (the order of appearance doesn't matter)
> Is it even possible to do this with regular expressions? Or should I first
> look if there is some kind of match and then apply an
> str_replace($match,'',$string) and add the $match again?
>
> Greetings !
>

Assuming the duplicate segments are identical.....
I'd use explode() and convert the string to an array. Use "}" for the delimiter.
Then use array_unique()
And then use implode() to restore the string.



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Re: strip out repeated ocurrence of a string

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On Tue, 2010-01-26 at 07:56 -0500, Al wrote:

>
> On 1/25/2010 10:48 PM, Camilo Sperberg wrote:
> > Hello list :)
> >
> > I have this problem, a certain string can contain the following information:
> >
> >
> > $string = '
> > hi{value1;value2}
> > bye{value1;value3}
> > hi{value1;value4}
> > hi{value1;value2}
> > bye{value1;value2}
> > ';
> >
> > What I want is to be able to get this result:
> >
> > $string = '
> > hi{value1;value2}
> > bye{value1;value3}
> > hi{value1;value4}
> > bye{value1;value2}
> > ';
> >
> > (the order of appearance doesn't matter)
> > Is it even possible to do this with regular expressions? Or should I first
> > look if there is some kind of match and then apply an
> > str_replace($match,'',$string) and add the $match again?
> >
> > Greetings !
> >
>
> Assuming the duplicate segments are identical.....
> I'd use explode() and convert the string to an array. Use "}" for the delimiter.
> Then use array_unique()
> And then use implode() to restore the string.
>
>
>


Just did a bit of hunting as I know I've seen something similar to what
you're asking before.

If you're on a Linux system, try this:

awk '!x[$0]++' inputfile > outputfile

This seems to be the best way to remove duplicate lines and still
preserve the original order of the unique lines.

Thanks,
Ash
http://www.ashleysheridan.co.uk



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Re: strip out repeated ocurrence of a string

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>
> a certain string can contain the following information:
>>
>> $string =
>> 'hi{value1;value2}bye{value1;value3}hi{value1;value4}hi{valu e1;value2}bye{value1;value2}';
>>
>> What I want is to be able to get this result:
>>
>> $string =
>> 'hi{value1;value2}bye{value1;value3}hi{value1;value4}bye{val ue1;value2}';
>>
>> (the order of appearance doesn't matter)
>>
>
> Assuming the duplicate segments are identical.....
> I'd use explode() and convert the string to an array. Use "}" for the
> delimiter.
> Then use array_unique()
> And then use implode() to restore the string.
>

Really nice solution indeed :D I didn't know array_unique() (well, that's
not entirely true, I had read about it once or twice, but didn't remembered
it).

Anyway, I remembered after I sended the mail that the order DO matter, but
that is just reversing an array :)
Just for the record, the applied code is:

$string =
implode('}',array_reverse(array_unique(array_reverse(explode ('}',$string)))));

First, an explode of the string to create an array, than I reverse it so
that the last ocurrence of the repeated part will always be last, after that
I apply array_unique, de-reverse it and implode it all back together as a
string.

Result?
input:
hi{value1;value2}bye{value1;value3}hi{value1;value4}hi{value 1;value2}bye{value1;value2}

output:
bye{value1;value3}hi{value1;value4}hi{value1;value2}bye{valu e1;value2}


Thank you very much !


@Ashley: It must be done in PHP, because it should run in any environment.
But thanks anyway, any help is apreciated: you just saw that there was a
much easier way than trying to use regular expressions or str_replace when
using arrays is considerably faster (especially because the $string won't be
a few bytes, it could range from ~5 bytes up to ~300+ KiB).

Greetings!

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Mailed by:
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