awk | Rearrange fields of CSV file on the basis of column value - awk

Question

I need you help in writing awk for the below problem. I have one source file and required output of it.
Source File
a:5,b:1,c:2,session:4,e:8
b:3,a:11,c:5,e:9,session:3,c:3
Output File
session:4,a=5,b=1,c=2
session:3,a=11,b=3,c=5|3
Notes:
Fields are not organised in source file
In Output file: fields are organised in their specific format, for example: all a values are in 2nd column and then b and then c
For value c, in second line, its coming as n number of times, so in output its merged with PIPE symbol.
Please help.

Answer 1

Will work in any modern awk:
$ cat file
a:5,b:1,c:2,session:4,e:8
a:5,c:2,session:4,e:8
b:3,a:11,c:5,e:9,session:3,c:3
$ cat tst.awk
BEGIN{ FS="[,:]"; split("session,a,b,c",order) }
{
split("",val) # or delete(val) in gawk
for (i=1;i<NF;i+=2) {
val[$i] = (val[$i]=="" ? "" : val[$i] "|") $(i+1)
}
for (i=1;i in order;i++) {
name = order[i]
printf "%s%s", (i==1 ? name ":" : "," name "="), val[name]
}
print ""
}
$ awk -f tst.awk file
session:4,a=5,b=1,c=2
session:4,a=5,b=,c=2
session:3,a=11,b=3,c=5|3
If you actually want the e values printed, unlike your posted desired output, just add ,e to the string in the split() in the BEGIN section wherever you'd like those values to appear in the ordered output.
Note that when b was missing from the input on line 2 above, it output a null value as you said you wanted.

Answer 2

Try with:
awk '
BEGIN {
FS = "[,:]"
OFS = ","
}
{
for ( i = 1; i <= NF; i+= 2 ) {
if ( $i == "session" ) { printf "%s:%s", $i, $(i+1); continue }
hash[$i] = hash[$i] (hash[$i] ? "|" : "") $(i+1)
}
asorti( hash, hash_orig )
for ( i = 1; i <= length(hash); i++ ) {
printf ",%s:%s", hash_orig[i], hash[ hash_orig[i] ]
}
printf "\n"
delete hash
delete hash_orig
}
' infile
that splits line with any comma or colon and traverses all odd fields to save either them and its values in a hash to print at the end. It yields:
session:4,a:5,b:1,c:2,e:8
session:3,a:11,b:3,c:5|3,e:9