sum up values from each columns (awk)

lcvs · 06-19-2012, 02:27 AM

I have different files with variable numbers of columns.

What I try to do is to output the values of each columns:
- with the single value if it is the same in the entire column,
- or the values separated by "," if it exist different ones in the same column

example 1:
input:
1|2|3|4
1|1|3|4
1|2|3|3

output:
1|1,2|3|3,4

example 2:
input:
1|2
1|3
7|2

output:
1,7|2,3

(the order of numbers separated by "," doesn't matter)

Thanks for your help !

pan64 · 06-19-2012, 03:26 AM

you can define associative arrays for every column: col1, col2, col3, col4. line is automatically split into $1, $2, $3 ... (-F\| is used to define separator). col1[$1] = 1; col2[$2] = 2 ... will define the element of arrays. finally (using END) you need to print the defined elements of those arrays

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lcvs · 06-19-2012, 04:10 AM

Hi Pan 64, thanks for your help !

I am not sure to understand the term "associative array".
Is it the same as an array that you define when using the split function?

If we look at the first input I wrote:

Code:

1|2|3
1|1|3
1|2|3

Are these values equivalent to these elements below?

Code:

col1[$1]|col2[$1]|col3[$1]
col1[$2]|col2[$2]|col3[$2]
col1[$3]|col2[$3]|col3[$3]

pan64 · 06-19-2012, 04:14 AM

see here, you will find some useful tips

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lcvs · 06-19-2012, 08:09 AM

ok, associative arrays are still not very clear for me, but maybe something that would look like that:

Code:

BEGIN{FS=OFS="|"}

{
    for (i=1; i<=NF; i++){
        coli[$i]++
            if(coli[$i] <is unique????>){
                print $i}

            else
                print coli[$i] <with a "," somewhere ?????>
}
}

pan64 · 06-19-2012, 10:38 AM

that's fine, you are almost ready.

Code:

function printarray (a)
{
    for (i=1; i<=length(a); i++)
    {
        print a[i];
        if ( i<length(a) ) printf ",";
    }  
}

this will print an array. Hope this helps

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chrism01 · 06-19-2012, 06:59 PM

An associative array is often referred to as a hash table, although strictly speaking one is an implementation of the other

https://en.wikipedia.org/wiki/Associative_array

Quote:

In computer science, an associative array, map, or dictionary is an abstract data type composed of a collection of (key,value) pairs, such that each possible key appears at most once in the collection.
.
.
.
The dictionary problem is the task of designing a data structure that implements an associative array. A standard solution to the dictionary problem is a hash table;

https://en.wikipedia.org/wiki/Hash_table

Quote:

Thus, a hash table implements an associative array.

lcvs · 06-20-2012, 01:18 AM

Quote:

Code:

function printarray (a)
{
    for (i=1; i<=length(a); i++)
    {
        print a[i];
        if ( i<length(a) ) printf ",";
    }
}

- What is the point of "function printarray (a)" ?
- Why we don't mention fields?
- Does "length" refers to the length of array a, in other words the number of lines in the column?

pan64 · 06-20-2012, 02:19 AM

this function will print the list of the values of the array passed to the func (separated by a comma). We do not need fields, records and other funny things, just a for loop. length is a built-in function (of awk), it will return the length of a string or the length of an array (see man page).

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lcvs · 06-20-2012, 04:03 AM

I don't really see where I am going with that.
I need to learn a bit more I guess.

Thanks anyway !

pan64 · 06-20-2012, 04:16 AM

the function is used to print col1, col2, col3 and col4, the four arrays where you collected your data

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