awk , conditional involving line and column


 
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# 1  
Old 02-25-2012
awk , conditional involving line and column

Dear All,

I indeed your help for managing resarch data file.

for example I have,

data1.txt :

type of atoms z vz
Si 34 54
O 20 56
H 14 13
Si 40 17
O 65 18
H 70 19
Si 24 20
H 85 21
O 90 12
Si 12 34

I want to extract O and H data using awk where its z value is bigger than maximum z value of Si (40).
that I hope I can data file, say data2.text:
type of atoms z vz
O 65 18
H 70 19
H 85 21
O 90 12

thank you in advance
with best regards,

---------- Post updated at 08:19 PM ---------- Previous update was at 08:13 PM ----------

sorry, once more, I also need the opposite one.
data3.test

Si 34 54
O 20 56
H 14 13
Si 40 17
Si 12 34
# 2  
Old 02-25-2012
Hello ariesto ,

Can you try the below command line .
Code:
 
 
maxSi=`awk '$1 ~/Si/{if(max < $2){max = $2}}END{print max}' data1.txt`;awk -v val=$maxSi '$1 ~ /O/ || $1 ~ /H/{if ($2 > val){print $0}}' data1.txt

# 3  
Old 02-25-2012
I think this will do what you want. Reads data1.txt and generates data2.txt and data3.txt. I was a bit confused with your example of data3 -- I assumed you meant that it should have anything not written to data2.txt.

Code:
awk '
    NR == 1 { print >"data2.txt"; print >"data3.txt"; next; }   # needed if there is a header line
    {
        if( $1 == "Si"  &&  $2+0 > simax )
            simax = $2 + 0      # take note of max value 

        capture[++idx] = $0;   # capture for output lines
        type[idx] = $1;            # save type and value for easy check at end
        value[idx] = $2+0;
    }

    END {
        for( i = 1; i <= idx; i++ )     # for each input line we saw put it someplace based on the z value 
        {
            dest = ((type[i] == "O" || type[i] == "H") && value[i] > simax ) ? "data2.txt" : "data3.txt";
            print capture[i] >dest;
        }
    }
' data1.txt


Last edited by agama; 02-26-2012 at 03:33 PM.. Reason: Realised your input has a header, didn't deal with that initially; consistency change on assignment of value.
# 4  
Old 02-25-2012
A shorter version

Code:
 
awk '$1 ~/Si/{if(max < $2){max = $2}} $1 ~ /O/ || $1 ~ /H/{if ($2 > max){print $0}}'

# 5  
Old 02-25-2012
Quote:
Originally Posted by codemaniac
A shorter version

Code:
 
awk '$1 ~/Si/{if(max < $2){max = $2}} $1 ~ /O/ || $1 ~ /H/{if ($2 > max){print $0}}'

@codemaniac: your shorter version doesn't work for the case below:

Code:
type of atoms z vz
Si 34 54
O 35 56
H 14 13
Si 40 17
O 65 18
H 70 19
Si 24 20
H 85 21
O 90 12
Si 12 34

The first O value is larger than the previous Si, but not larger than the maximum Si value in the file; your script will print it because it's larger than the previously observed Si value.
This User Gave Thanks to agama For This Post:
# 6  
Old 02-25-2012
Thanks Agama for pointing this out , I was in the illusion that if there are two body {}
blocks in an awk , then second will start only if first one parses all the records of a file .

Can you give some more enlightment on how awk processes multiple body blocks . {}
# 7  
Old 02-26-2012
Quote:
Originally Posted by codemaniac
Thanks Agama for pointing this out , I was in the illusion that if there are two body {}
blocks in an awk , then second will start only if first one parses all the records of a file .

Can you give some more enlightment on how awk processes multiple body blocks . {}
I don't want to hijack this thread, so I'll just post a link to a pretty decent on-line overview of awk. If you still have questions, create a thread in shell programming and someone will be eager to expand further.

Awk - A Tutorial and Introduction - by Bruce Barnett
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