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apply a function twice successively with the same input in awk program

 
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Top Forums UNIX for Dummies Questions & Answers apply a function twice successively with the same input in awk program
# 8  
Old 09-19-2012
OK, i try with an example.

This thread can be related with this one:
https://www.unix.com/unix-dummies-que...#post302702771

Let's say we have a one-record input like that:
Code:
abcdef

I would like to convert to numbers blocks of 2 letters (for which I defined a function) by starting from the first letter, than the second, then the third, then the fourth, etc

conversion table:
Code:
conv["ab"]="1"; conv["bc"]="2"; conv["cd"]="3"; conv["de"]="4"; conv["ef"]="5"

to get this output:
for i=1 (starting from 1st letter)
Code:
135

for i=2 (starting from 2nd letter)
Code:
24X

etc.

But every time I modify the value of "i" I have to use the original input (not the output from the previous call)
Code:
BEGIN {conv["ab"]="1"; conv["bc"]="2"; conv["cd"]="3"; conv["de"]="4"; conv["ef"]="5"}
    
function convert(i)   
    {
        numb = ""
        do{
            letter = substr($1, i, 2)
            numb = numb (letter in conv ? conv[letter] : "X")
            i=i+2}
        while(letter!="")
        return $1=numb
    }

    { print convert(1) }     # use original input
    { print convert(2) }     # use also original input
    etc.


I hope it helps you to see my point !
# 9  
Old 09-19-2012
So you want the value of i to keep increasing with each call?

Don't make it a parameter then, and it will be a global variable.
# 10  
Old 09-19-2012
Quote:
So you want the value of i to keep increasing with each call?
Yes, until a certain limit though.

Quote:
Don't make it a parameter then, and it will be a global variable.
So what you are suggesting is that I shouldn't mention the "i" parameter in the function, and use a for loop to assign a value to "i" instead?

something like that maybe:
Code:
BEGIN {conv["ab"]="1"; conv["bc"]="2"; conv["cd"]="3"; conv["de"]="4"; conv["ef"]="5"}
    
function convert  (letter) 
    {
        numb = ""
        do{
            letter = substr($1, 1, 2)
            numb = numb (letter in conv ? conv[letter] : "X")
            }
        while(letter!="")
        return $1=numb
    }

    { for (i=1; i<=5; i++){
           letter=substr($1,i,2)
           convert(letter)
           }
    }1

but it will only consider the first block...
# 11  
Old 09-19-2012
I'm saying to not use a loop for it at all. Just increment it in the function itself.
# 12  
Old 09-20-2012
How can you increment in the function itself without a for loop????

The only way I see how to do that is like:
Code:
BEGIN {conv["ab"]="1"; conv["bc"]="2"; conv["cd"]="3"; conv["de"]="4"; conv["ef"]="5"}


function convert(letter){
        numb = ""
        for(start=1; start<=5; start++){
            ss = substr(letter, start, 2)
            while( ss != "" ){
               numb = numb (ss in conv ? conv[ss] : "X")
               start = start + 2
               ss = substr(letter, start, 2)
           }
        }
        return numb
    }

{ $1 = convert($1);
   print $1}

Last edited by beca123456; 09-21-2012 at 06:40 AM..
# 13  
Old 09-21-2012
Stop bumping your posts. It doesn't make answers faster.

i=i+1?

If that won't do, then I don't understand your problem.
# 14  
Old 09-22-2012
Sorry!

For each line of the input, I need to convert the string starting from the first letter, then starting from the second letter, then the third, etc.

input:
Code:
abcdef

ouput:
Code:
135   # starting from the first letter (i.e. "abcdef")
24X   # starting from the second letter (i.e. "bcdef")
35     # starting from the third letter (i.e. "cdef")
4X     # starting from the fourth letter (i.e. "def")
5       # starting from the fifth letter (i.e. "ef")

I tried:
Code:
BEGIN {conv["ab"]="1"; conv["bc"]="2"; conv["cd"]="3"; conv["de"]="4"; conv["ef"]="5"}


function convert(letter){
        for(i=1; i<=5; i++){
                numbi = ""
                l = length(letter)
                stringi = substr(letter, i, (l-i)+1)        
                ss = substr(stringi, start, 2)
                while(ss != ""){
                        numbi = numbi (ss in conv ? conv[ss] : "X")
                        start = start + 2
                        ss = substr(stringi, start, 2)
                }
        return numbi
        }
}

{ $1 = convert($1);
   print $1}


But it returns only the first increment (and it is wrong).
 
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