topic Re: Pattern recognition in a given string in Application Development and Automation Discussions

Pattern recognition in a given string

venkatesha_n — Wed, 21 Dec 2011 11:31:25 GMT

Hi Experts,

I have one problem in finding a repeated pattern in a given string.

For example: if the given string lv_string = '345723345982343452343345'.

you can check the lv_string, which contains '345' repeatedly in it.

so, i want a ABAP code to get list of all such type of patterns repeated in a given string.

Thanks in advance.

Venky.

Re: Pattern recognition in a given string

kesavadas_thekkillath — Wed, 21 Dec 2011 11:38:35 GMT

Hey F1 ... Please help Venkatesa .

Re: Pattern recognition in a given string

venkatesha_n — Wed, 21 Dec 2011 11:42:12 GMT

Its not there in F1 Help......

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 11:50:57 GMT

You have to Find it.

Re: Pattern recognition in a given string

venkatesha_n — Wed, 21 Dec 2011 11:57:06 GMT

Hello,

its not just CP / CA / NP / CO... etc.

And also am not talking about regular expressions which we normally do by using cl_abap_matcher or cl_abap_regex.

Try to understand the problem first:

NOTE: you are given just a string and nothing else and you will not be given any search key/ pattern to be found.

we have to search the given string so that, what part of string is repeated again and again.

I hope this is enough to understand the problem.

thanks

Venky.

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 11:59:22 GMT

To be fair to the OP, the question is not trivial.

I challenge everyone here to write code to detect a string with patterns repeated more than once in the string. The pattern can be anything and is not known at design time.

Hint: Regular expressions may be a key and normal ABAP pattern matching is not much use

There are some programming snippets on the Web, though not in ABAP but still may be useful

http://social.msdn.microsoft.com/Forums/en/csharpgeneral/thread/037047fc-5506-4656-ad27-dab9a6c501ee

Edited by: Vishnu Tallapragada on Dec 21, 2011 1:01 PM

I just realize, the OP and I posted together

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:06:16 GMT

data: lv_string type string.
data: mcnt type i.
lv_string = '345723345982343452343345'.

find ALL OCCURRENCES OF '345' in lv_string MATCH COUNT mcnt.

write: / mcnt.

Did i win cookies?

Re: Pattern recognition in a given string

kesavadas_thekkillath — Wed, 21 Dec 2011 12:06:39 GMT

Vishnu,

The code is readily available in F1 help FIND - pattern

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:09:24 GMT

Keshav and Maen - sorry but you still don't seem to get it.

We don't know what the pattern is.

We want to detect a string with repeated patterns, the pattern we don't know in advance.

It can be anything

345w2343234523

Vishnudoesn'tlikeVishnu

Re: Pattern recognition in a given string

venkatesha_n — Wed, 21 Dec 2011 12:10:56 GMT

Hello Maen Anachronos ,

Please try to understand the problem..

I have already told that, you will be given just a big string like this '345723345982343452343345'.

And you have to find out what part of the string is repeated again and again in the given string.

and if there are multiple such parts of the string, which are repeated in a given string.

all that repeated substrings should be the output...

Interesting?....

Thanks,

Venky.

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:11:40 GMT

Using the FIND statement it should be easy to program the stuff. Even if the serach string is not given.

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:12:20 GMT

dude just use all occurences you will find the solution

FIND ALL OCCURRENCES OF '345' in lv_string MATCH COUNT var

Cheers

NZAB

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:12:42 GMT

Ow but i do understand.

Point is: you need to be creative to use the FIND statement.

Re: Pattern recognition in a given string

kesavadas_thekkillath — Wed, 21 Dec 2011 12:14:14 GMT

Vishnu,

See this example in documentation


DATA: patt       TYPE string VALUE `now`, 
      text       TYPE string, 
      result_tab TYPE match_result_tab. 

FIELD-SYMBOLS <match> LIKE LINE OF result_tab. 


FIND ALL OCCURRENCES OF patt IN 
     `Everybody knows this is nowhere` 
     RESULTS result_tab. 

LOOP AT result_tab ASSIGNING <match>. 
  WRITE: / <match>-offset, <match>-length. 
ENDLOOP.

Mods-Sorry for pasting the standard code, did just in case to demonstrate that Its as simple as that

@OP- No Points please

Re: Pattern recognition in a given string

venkatesha_n — Wed, 21 Dec 2011 12:14:27 GMT

Hello NZAB,

Can you please go through the problem properly....?

Thanks.

Venky.

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:15:31 GMT

He doesn't know if it is 345 or Vishnu or Maen or Keshav, that can repeat in the string.

He just wants to know if a pattern (which can be anything) is repeating in a string, if so what is (are) those. Not an easy problem.

Keshav, he doesn't know if it is "now" that can repeat in his string. It can be "now" or "then" or "here" or "there", can be anything

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:18:07 GMT

data: gv_string type string.
data: gv_length type i.
data: gv_offset type i.
data: gv_search type string.
data: mcnt type i.


gv_string = '345723345982343452343345'.
gv_length = strlen( gv_string ).

write: / gv_string.

gv_offset = 0.
do gv_length times.
  if gv_offset eq 0.
    gv_search = gv_string(1).
  else.
    concatenate gv_search gv_string+gv_offset(1) into gv_search.
  endif.

  find ALL OCCURRENCES OF gv_search in gv_string MATCH COUNT mcnt.
  write: /'Search for', gv_search, 'counted', mcnt.

  gv_offset = gv_offset + 1.

enddo.

Now i expect a really big cake instead of a cookie.

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:20:09 GMT

Maen, I guess, it will work, but it is not very efficient.

Re: Pattern recognition in a given string

kesavadas_thekkillath — Wed, 21 Dec 2011 12:21:26 GMT

I have provided that standard code...Did anybody look into it

Re: Pattern recognition in a given string

Former Member — Wed, 21 Dec 2011 12:21:32 GMT

hehe... and why not? It's not like he's going to search for repeating patterns in the holy bible.

And the challenge was: write a piece of code to do it.