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how to match a paragraph by regexp?

Question posted by: poolboi (Familiar Sight) on May 13th, 2008 06:13 AM
hey guys,

another regexp problem which i'm probably not good at here goes
my text file has this


Code: ( text )
  1. /* 1 TB VTP-1 SESSION=01547 USERID STARTED 2008-05-13 09:46:11 */
  2. I AM A GIRL
  3.  /* 3 SESSION=01547 USERID 2008-05-13 09:46:12 */
  4.  /* 4c COMMAND EXECUTED */
  5.  /* 4c SESSION=01547 USERID=SASTST 2008-05-13 09:46:12 */
  6.  /* 2 TB HLRi VTP-1 SESSION=01547 USERID ENDED 2008-05-13 09:47:12 */
  7.  /* 1 TB VTP-1 SESSION=01547 USERID STARTED 2008-05-13 09:46:11 */
  8.  I AM A BOY
  9.  /* 3 SESSION=01547 USERID 2008-05-13 09:46:12 */
  10.  /* 4c COMMAND EXECUTED */
  11.  /* 2 TB HLRi VTP-1 SESSION=01547 USERID ENDED 2008-05-13 09:47:12 */


if u see it's like 2 paragraphs
i need to match the paragraphs as u can see each paragraph starts with "1 TB" and end with "2 TB" how can i match the one paragraph?

previously i was using this to match but this one only go through one line
how can i make it match a paragraph?

Code: ( text )
  1. foreach $data1 (@$data)
  2. {
  3. chomp ($data1);
  4.  
  5. if ($data1 =~ /1 TBHLR.+word/){ ## i replace the word with anything i wanna match
Last edited by eWish : May 13th, 2008 at 12:55 PM. Reason: Added code tags
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nithinpes's Avatar
nithinpes
Expert
234 Posts
May 13th, 2008
08:48 AM
#2

Re: how to match a paragraph by regexp?
Since the paragraphs are not like typical paragraphs, one way to do it is that you need to process the array containing the file-input to get an array in which each element is a paragraph and not a line.
Code: ( text )
  1. open(IN,"data.txt")or die "failed:$!";
  2. @file=<IN>;
  3. foreach(@file) {
  4.  if(/1 TB/) {$str = $_ ; next;} ## look for lines with '1 TB'
  5. unless(/2 TB/) {
  6.    $str.=$_  ;     ## append lines until line with '2 TB' is reached
  7. }
  8. else {
  9. $str.= $_ ;
  10. push @data,$str;   ## on reaching '2 TB' push the concatenated string to array
  11. undef $str;
  12. } 
  13. }
  14.  
  15. #print "\n\n$_\n\n" foreach(@data);
  16. foreach $data1 (@data)
  17. {
  18. ##### $data1 will be a paragraph now
  19.  
  20. }
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poolboi's Avatar
poolboi
Familiar Sight
170 Posts
May 14th, 2008
02:27 AM
#3

Re: how to match a paragraph by regexp?
great thanks!

erm just some clarification

the opertor ".=" is an overload operator right? meaning to say it appends yr previous data

and what's the use of putting undef $str??

correct me if i'm wrong
:)
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poolboi's Avatar
poolboi
Familiar Sight
170 Posts
May 14th, 2008
02:41 AM
#4

Re: how to match a paragraph by regexp?
Quote:
Originally Posted by nithinpes
Since the paragraphs are not like typical paragraphs, one way to do it is that you need to process the array containing the file-input to get an array in which each element is a paragraph and not a line.
Code: ( text )
  1. open(IN,"data.txt")or die "failed:$!";
  2. @file=<IN>;
  3. foreach(@file) {
  4.  if(/1 TB/) {$str = $_ ; next;} ## look for lines with '1 TB'
  5. unless(/2 TB/) {
  6.    $str.=$_  ;     ## append lines until line with '2 TB' is reached
  7. }
  8. else {
  9. $str.= $_ ;
  10. push @data,$str;   ## on reaching '2 TB' push the concatenated string to array
  11. undef $str;
  12. } 
  13. }
  14.  
  15. #print "\n\n$_\n\n" foreach(@data);
  16. foreach $data1 (@data)
  17. {
  18. ##### $data1 will be a paragraph now
  19.  
  20. }


hm...nithinpes
sorry, i think there could be a problem
cos say i wanna just the paragraph from "1 TB" to "Command Execute"
i just change to :

Code: ( text )
  1. foreach (@file)
  2. {
  3. if(/1 TB/) {$str = $_; next;}
  4. unless (/COMMAND EXECUTED/){
  5.     $str.=$_;
  6. }else{
  7. $str.=$_;
  8. push @data,$str;
  9. undef $str;
  10. }
  11. }
  12.  
  13. print "$_" foreach(@data);


but it still prints everything as per normal
it doesn't print the paragraph from "TB 1" to "COMMAND EXECUTED"
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poolboi's Avatar
poolboi
Familiar Sight
170 Posts
May 14th, 2008
02:47 AM
#5

Re: how to match a paragraph by regexp?
sorrie sorrie i define something wrongly in the earlier part of my script
alright it's working
thanks :)
u can go back to my previous question on "undef" and ".="
many thanks
:)
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nithinpes's Avatar
nithinpes
Expert
234 Posts
May 14th, 2008
04:12 AM
#6

Re: how to match a paragraph by regexp?
Quote:
Originally Posted by poolboi
great thanks!

erm just some clarification

the opertor ".=" is an overload operator right? meaning to say it appends yr previous data

and what's the use of putting undef $str??

correct me if i'm wrong
:)


The operator ".=" is used in string concatention context.For ex:
Code: ( text )
  1. $a = "Hello";
  2. $b= " poolboi";
  3. $c= $a.$b;
  4. print $c;  ## prints "Hello poolboi"

In this case,
Code: ( text )
  1. $str.=$_;
is equivalent to
Code: ( text )
  1. $str=$str.=$_;


Regarding 'undef $str'. This is used to undefine $str(delete previously stored value) inorder to avoid concatenating string for the next paragraph to previous paragraph(string).
But this line is actually irrelevant in the above code as the line:
Code: ( text )
  1. if(/1 TB/) {$str = $_ ; next;}

will redefine/reassign the value from scratch whenever a line with '1 TB' pattern is seen.
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poolboi's Avatar
poolboi
Familiar Sight
170 Posts
May 14th, 2008
06:47 AM
#7

Re: how to match a paragraph by regexp?
hm..thanks for the explanation

hm..just discovered a problem
it's similar to on top

i got these info in my textfile now

Code: ( text )
  1. /* 3 SESSION=01547 USERID=user 2008-05-13 09:46:12 */
  2.  /* 4 ABC:DEFG=12334556,BSERV=T22; */
  3.  /* 4c COMMAND EXECUTED */
  4.  /* 1 TBHLR HLRi VTP-11 SESSION=01548 USERID=user STARTED 2008-05-


wheni use this code:
Code: ( text )
  1. foreach $data1 (@$data)
  2.     {
  3.       chomp ($data1);
  4.     if ($data1 =~ /4 \D\D\D:/ && $data1 !~ /3 SESSION/ && $data1 !~ /4c COMMAND/){
  5.       print "$data1\n"; 
  6. }

it returns me

/* 4 ABC:DEFG=12334556,BSERV=T22; */

but when i use the paragraphing code...

Code: ( text )
  1. foreach (@file)
  2. {
  3. if(/3 SESSION/) {$str = $_; next;}
  4. unless (/4c COMMAND/){
  5.     $str.=$_;
  6.  
  7. }else{
  8. $str.=$_;
  9. push @data,$str;
  10. undef $str;
  11. }}
  12.  
  13. foreach $data1 (@data)
  14. {
  15. if($data1 =~ /4c \D\D\D:/ && $data1 !~ /3 SESSION/ && $data1 !~ /4c COMMAND/){
  16.       print "$data1\n"; 
  17.      
  18. }}

nothing returns

is there a problem with the 2nd code? i suppose it's suppose to return the same for both
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nithinpes's Avatar
nithinpes
Expert
234 Posts
May 14th, 2008
08:53 AM
#8

Re: how to match a paragraph by regexp?
That's the expected behaviour. In your first code, your are matching with one line at a time. Hence, it returns the line

/* 4 ABC:DEFG=12334556,BSERV=T22; */

which fits all the three matching conditions that you have put.
But in the second code, you are taking one paragraph at a time. So, for the first iteration $data1 will be
/* 3 SESSION=01547 USERID=user 2008-05-13 09:46:12 */
/* 4 ABC:DEFG=12334556,BSERV=T22; */
/* 4c COMMAND EXECUTED */
which doesn't return true for all the 3 match conditions.
Last edited by nithinpes : May 14th, 2008 at 08:55 AM. Reason: removed initial quote
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