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Full Discussion: Awk: Performing "for" loop within text block with two files
Top Forums UNIX for Beginners Questions & Answers Awk: Performing "for" loop within text block with two files Post 303029186 by Don Cragun on Wednesday 23rd of January 2019 12:30:26 AM
Old 01-23-2019
Quote:
Originally Posted by Scrutinizer
You are welcome jvoot.

Don is right of course and it all depends what it is that you require.

To illustrate, to add the additional requirements, you could try these adjustments, which makes the code more precise, but more complex.
Code:
awk '
  NR==FNR {
    Keys[$1,$2]
    next
  }
  /<Co>/ { 
    for(line=1; line<=NF; line++) {
      split($line,Fields," ")
      if(line==1)
        subkey1=Fields[1]
      if(Fields[1]=="Lexeme") {
        for(i in Fields)
          if((subkey1,Fields[i]) in Keys) {
            print
            next
          }
        }
      }
    }
' file1 FS='\n' RS= ORS='\n\n' file2

How much precision you need depends on the variability of your input files. So to understand the limitations, you need to understand both your data and your code and you need to test of course.

This approach uses RS=, which is a special case, where an empty line (two consecutive newlines) is used as a record separator. The additional requirements, meant that the field separator FS needed to be changed to a newline, so that each field constitutes a line within a record in file2. These lines then needed to be split into smaller subfields using the split() command.

Each approach has its pros and cons.

A pro of this approach may be that the code can be simpler, so it may be easier to understand.

The cons are:
  • Adding more precision can sometimes lead to more complexity than a line based approach.
  • If there is so much as a space or TAB character on any of the empty lines, then it may break the solution..

You need to weigh these considerations when choosing your approach. It all depends..
Hi Scrutinizer,
You and I interpreted the requirement from post #1:
Quote:
My hope was that when $1 of File 1 matches $1 in File 2, $0 in File 2 contains the string "<Co>", and $2 of File 1 matches a string *exactly* in File 2 on a line beginning with the word "Lexeme," then print.
differently. You interpreted "when $1 of File 1 matches $1 in File 2, $0 in File 2 contains the string "<Co>"" to mean that "<Co>" has to appear somewhere in the multi-line record while I interpreted it to mean that "<Co>" has to appear in the line where $1 in File 1 matches $1 in File 2.

If we change the line in your code that is:
Code:
  /<Co>/ {

to be:
Code:
  $1 ~ /<Co>/ {

then I believe that your code and my code would produce the same results.

I also believe that changing the two lines in my code:
Code:
	if(PrintThisGroup) {
	... ... ...
++LinesInGroup == 1 && /<Co>/ {

to be:
Code:
	if(PrintThisGroup && Group ~ /<Co>/) {
	... ... ...
++LinesInGroup == 1 {

would make my code produce the same output as your code. I'm afraid jvoot will have to clarify the requirements for us to determine which one of us guessed correctly at the desired behavior.

Until I saw the sample record containing two "Lexeme" lines and two "ClauseType" lines, I had started trying a different approach (assuming that line 2 of a multi-line record in File 2 had to be the one and only "Lexeme" line in a record) that was closer to jvoot's original code. That method might have been easier for jvoot to follow, but since the given sample didn't match what I was expecting, I abandoned that approach.

It isn't surprising that we chose different approaches to solving the problem based on our different interpretations of the requirements. Clearly, there are lots of ways to address this problem.

Cheers,
Don
This User Gave Thanks to Don Cragun For This Post:
Neo
 

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