How to calculate a sum of certain records? - Page 2 - Shell Programming and Scripting

vino · #8 06-10-2005

You could use awk, but then you have a requirement to find the frequency based on the first 2 characters of the 4th field.

I am not sure, how you can extract characters using awk.

Probably someone could post a solution for that.

Vino

r2007 · #9 06-10-2005

Code:

awk -F"\t" '{a[substr($4,1,2)]++}END{for (i in a) print i,a[i]}'

sickboy · #10 06-10-2005

Quote:

Originally Posted by r2007

for 2nd question:

Code:

awk -F"\t" '{a[$3]+=$2}END{for (i in a) print i,a[i]}'

[not test]

Thanks a lot. It is working properly but I cannot understand how it is working.

When you this
a[$3]+=$2
this means that you put the 3rd field in a table and you assign his value to be equal with the sum of its second field?????
And why we don't get many times the same 3rd field when printing (I don't want to be printed many times, I just want to understand how it is working).

Cheers

r2007 · #11 06-10-2005

Quote:

AWK variables are dynamic; they come into existence when they are first used. Their values are either floating-point numbers or strings, or both, depending upon how they are used.
All arrays in AWK are associative, i.e. indexed by string values.

a[$3]+=$2 <===> a[$3]=a[$3]+$2
with the following data
386 8192 A423 CC0177 40
586 65536 A424 CC0182 670
486 16384 A423 CC0183 100
486 16384 A425 CC0184 80
65000 4096 B407 EE1027 80

AWK processes data line by line
line #1: a["A423"]=a["A423"]+8192=8129
line #2: a["A424"]=a["A424"]+65536=65536
line #3: a["A423"]=a["A423"]+16384=8129+16384
...
...
...

Sorry for my pool English. That's all what I can explain to you.

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