adding numbers together

[ZzapUK]

I have a file with the contents:

6128 105
4356 15139
7052 1
5508 25
6932 200
5548 11468
5100 0
6128 105
4356 15125
7052 1
5508 25
6932 199
5548 11437
5100 0

Each of first number is repeated twice. For example there are 2 occurances of 6128, 4356, etc. What I want to do is subtract the second numbers for each first number. For example to achieve the output:

6128 0
4356 14
7052 0
5508 0
6932 1
5548 31
5100 0

Can anyone tell me how I might be able to do that with AWK?

Thanks!

 

[feherke]

Hi

awk '{if(v[$1])v[$1]-=$2;else v[$1]=$2}END{for(i in v)print i,v[i]}' /input/file

Feherke.

http://rootshell.be/~feherke/

 

[PHV]

feherke, if(v[$1]) evaluates to false if exists but is zero.

awk '
{if($1 in a)a[$1]-=$2;else a[$1]=$2}
END{for(i in a)print i,a}
' /path/to/input


Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ181-2886

 

[feherke]

Hi

Ooops. Thanks. I missed that.

Feherke.

http://rootshell.be/~feherke/

 

[futurelet]

$1 in a { print $1, a[$1] - $2 ; next }
{ a[$1] = $2 }