regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[AngusC]

I have text like this:

some description here Status1
some other description Status2
some other interesting description Status1

I am using regex like this:

\(.*\)\([a-zA-Z]+\)$

with replacement text:

\1 ZZZ \2

And what I expected was:

some description here ZZZ Status
some other description ZZZ Fault
some other interesting description ZZZ Status

But instead I got:

some description here Statu ZZZ s
some other description Faul ZZZ t
some other interesting description Statu ZZZ s

I want my expected outcome, how do I do that?

What was wrong with my regex?




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Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[K.P. Huang]

Try this one (please ignorer all the double quote):

" \([a-zA-Z]+\)$"

There is a space before first \, then replaced by

" ZZZ \1"

There is also a space before ZZZ.

Your regex will match the last char from end of line, i.e. \([a-zA-Z]+\)$.

Zero or more char follow by \(.*\). You got the right result for your regex.

-- kphuanghk








2015-03-25 20:27 GMT+08:00 AngusC <anguscomber@gmail.com>:

> I have text like this:
>
> some description here Status1
> some other description Status2
> some other interesting description Status1
>
> I am using regex like this:
>
> \(.*\)\([a-zA-Z]+\)$
>
> with replacement text:
>
> \1 ZZZ \2
>
> And what I expected was:
>
> some description here ZZZ Status
> some other description ZZZ Fault
> some other interesting description ZZZ Status
>
> But instead I got:
>
> some description here Statu ZZZ s
> some other description Faul ZZZ t
> some other interesting description Statu ZZZ s
>
> I want my expected outcome, how do I do that?
>
> What was wrong with my regex?
>
>
>
>
> --
> View this message in context:
> http://emacs.1067599.n5.nabble.com/regex-a-zA-Z-not-working-as-expected-tp353090.html
> Sent from the Emacs - Help mailing list archive at Nabble.com.
>
>

Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[Yuri Khan]

On Wed, Mar 25, 2015 at 6:27 PM, AngusC <anguscomber@gmail.com> wrote:
> I have text like this:
>
> some description here Status1
>
> I am using regex like this:
>
> \(.*\)\([a-zA-Z]+\)$
>
> with replacement text:
>
> \1 ZZZ \2
>
> And what I expected was:
>
> some description here ZZZ Status
>
> But instead I got:
>
> some description here Statu ZZZ s

Your regex consists of two parts. The first part matches any sequence
of characters. The second part matches any non-empty sequence of basic
Latin letters. There are many ways to match your text with this regex.
Most regular expression engines use the maximum munch rule — i.e. the
first part tries to match as much of the string as possible while
still satisfying the regex.

Others have suggested adding a space to disambiguate the match.

Alternatively, you can make the first group non-greedy so that instead
of matching as much as possible it will match as little as possible:

\(.*?\)\([a-zA-Z]+\)$

(Note the question mark in the first group.)

Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[AngusC]

Thanks for the explanation.  

A space was easiest fix.

\(.*\)\( [a-zA-Z]+\)$




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Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[tomas]

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On Wed, Mar 25, 2015 at 05:27:08AM -0700, AngusC wrote:
> I have text like this:
> 
> some description here Status1
> some other description Status2
> some other interesting description Status1

(I assume the digits at the end of the lines just don't exist:
they disappear later in your post magically anyway ;-)

> I am using regex like this:
> 
> \(.*\)\([a-zA-Z]+\)$

I'll try to read the above aloud:

"First, try to match zero-or-more of anything, call that \1".
"Then try to match at least one character, right before the
end-of-line. Call that \2".

> with replacement text:
> 
> \1 ZZZ \2
> 
> And what I expected was:
> 
> some description here ZZZ Status
> some other description ZZZ Fault
> some other interesting description ZZZ Status

Hm. Just why? It seems you expected the *second* match to
be "as long as possible", but there's no way you told that:

> But instead I got:
> 
> some description here Statu ZZZ s
> some other description Faul ZZZ t
> some other interesting description Statu ZZZ s

Reading aloud the regexp as above makes those matches less
mysterious, doesn't it?

Now: what could you do? Perhaps you might say that you want
the first match to be as short as possible, like so:

  \(.*?\)\([a-zA-Z]+\)$

> I want my expected outcome, how do I do that?

Is that your expected outcome?

> What was wrong with my regex?

As often (it happens to me all the time!), it's just sloppy
specification in your head :-)

Regards
- -- tomás
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Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[Loris Bennett]

AngusC <anguscomber@gmail.com> writes:

> I have text like this:
>
> some description here Status1
> some other description Status2
> some other interesting description Status1
>
> I am using regex like this:
>
> \(.*\)\([a-zA-Z]+\)$
>
> with replacement text:
>
> \1 ZZZ \2
>
> And what I expected was:
>
> some description here ZZZ Status
> some other description ZZZ Fault
> some other interesting description ZZZ Status
>
> But instead I got:
>
> some description here Statu ZZZ s
> some other description Faul ZZZ t
> some other interesting description Statu ZZZ s
>
> I want my expected outcome, how do I do that?
>
> What was wrong with my regex?

Your first group is matching right up to the last penultimate character
and the second is match the last character.  Try adding a patter to
match a space between your groups.

Cheers,

Loris

-- 
This signature is currently under construction.

Re: regex: \(.*\)\([a-zA-Z]+\)$ - not working as expected

[Loris Bennett]

"Loris Bennett" <loris.bennett@fu-berlin.de> writes:

> AngusC <anguscomber@gmail.com> writes:
>
>> I have text like this:
>>
>> some description here Status1
>> some other description Status2
>> some other interesting description Status1
>>
>> I am using regex like this:
>>
>> \(.*\)\([a-zA-Z]+\)$
>>
>> with replacement text:
>>
>> \1 ZZZ \2
>>
>> And what I expected was:
>>
>> some description here ZZZ Status
>> some other description ZZZ Fault
>> some other interesting description ZZZ Status
>>
>> But instead I got:
>>
>> some description here Statu ZZZ s
>> some other description Faul ZZZ t
>> some other interesting description Statu ZZZ s
>>
>> I want my expected outcome, how do I do that?
>>
>> What was wrong with my regex?
>
> Your first group is matching right up to the last penultimate character

Sorry, that should just be "the penultimate character".

> and the second is match the last character.  Try adding a patter to
> match a space between your groups.
>
> Cheers,
>
> Loris

-- 
Dr. Loris Bennett (Mr.)
ZEDAT, Freie Universität Berlin         Email loris.bennett@fu-berlin.de