How to use awk or sed to convert csv diffs into more readable format

Question

Can anyone give me the example of how to use awk or sed (not sure which one, as I haven't use either of these much, as I have mostly been using grep and cut to work with csv data) to convert differences between two .csv files into something more readable.

e.g. if I have a generated a diff from old and new .csv files, which in a real life could be much more complex because of a large number of columns:

2,3c2,3
< Barbara,1093,19
< Magdaline,2093,20
\ No newline at end of file
---
> Barbara,1011,19
> Magdaline,12093,20
\ No newline at end of file

how could I convert it to this format:

Barbara  1093 1011 
Magdaline 2093 12093

in a new format - a first column of data is a value from first column in both parts of the diff, to identify the line. Second column contains the data from the first csv file (old value) and third column - is the value from the second csv file (new value).

How can I perform such text conversion via awk or sed?

Thank you.

Answer 1

Use awk with two associative arrays. Something like this:

awk -F, '
  /^</{sub("< *","",$1);old[$1]=$2}
  /^>/{sub("> *","",$1);new[$1]=$2}
  END{ for(k in old) print k,old[k],new[k] }
'

You can concatenate that all into a one-liner separated by spaces if you prefer - but I like multiple lines. ;) Here's a sample:

sauer@humpy:~$ cat file
< a,b,c
> a,d,e
gibberish
< 1,2,3
> 1,4,5
sauer@humpy:~$ awk -F, '
  /^</{sub("< *","",$1);old[$1]=$2}
  /^>/{sub("> *","",$1);new[$1]=$2}
  END{ for(k in old) print k,old[k],new[k] }
' < file
a b d
1 2 4

Oh, if you have an old awk, the "< *" may need to be a fixed pattern rather than a regex, so lose the * and put in the literal amount of spaces after the directional indicator.