Programming

Thanks very much for that. Unfortunately i can't really understand it. Sorry, my knowledge of C is terrible. Where do i put the names of the two files i'm adding together. And what does nawk do? Thanks again for all your help.

Is that piece of code not just adding all the second column together? I need to add row1,column2 of file1 to row1,column2 of fille2;
row2,column2 of file1 to row2,column2 of fille2;
..3, ... 2 to .. 3, ... 2 ;
and so on, and put these new values into the second column of a new array, with the first column remaining the same in all the files.
Please if you can help me at all, i have to get this done real soon.
Thanks.

ok, here is what i am trying to understand
input data will come form 2 files, each having 4 columns, so if i merge it columnwise in a single file, I will have 8 columns, and the result should be a file containing 3*col2+2*col6
is that correct
to start with what you can do is merge the two files using the paste command and redirect the output to an intermediate third file
paste data1 data2 > data3

now data3 has 8 columns, the second column of first file data1 is in column position 2 of data3, and 2nd column of data2 is in column position 6 of data3

now what you need is 3*column2+2*column6. Is that right? if so then you use the command awk as below

awk '{printf("%e\n", (3*$2+2*$6))}' data3 > data4

now data4 is the final file

He does not want more columns. He wants to add the values in the columns across files. The only thing wrong with vger99's approach is that it doesn't ignore comments.

Code:

nawk '$1 = "%" { arr[$1] += $2 }
END {
  for ( i in arr )
     print i, arr[i]
}' myFile

On linux you probably use awk instead of nawk. $2 is the 2nd column. $1 is the first column. Look at your second data line... it would do "arr[5] += 3E-6". other data lines with a 5 in the first column get added to the same array element. At the end, all defined elements are displayed. Want to do two file? replace "myfile" with "myfile1 myfile2". It will loop over all input files. To do your ratios, mention one input file twice and the other three times.

to ignore 'comments' - assuming comments start with a '%' in the first character position:

Code:

nawk '/^[^%]/ { arr[$1] += $2 }
END {
  for ( i in arr )
     print i, arr[i]
}' myFile

About ignoring comments... I fixed mine. I am assuming $1 is a "%". (I had $! instead of $1). But I like vger99's better anyway.

Guys, you're absolute legends. I won't get to try it out til the morning, but if ye reckon it'll work thats good enough for me. One question though; The values in the first column range from 1E-2 to about 4E+4. Does your program just increment as it goes, or does it read in each $1 value itself. Either way will this program work with such small/large values? Thanks again.