Multiple values for a key in ksh

Question

I'm trying to read a file which is in pairs as follows:

V1#K1.@
V2#K1.@
V3#K2.@,V4#K1.@,V5#K2
V1#K3.@

My aim is to store it in key<=>pairs with # as a delimiter after removing '@' Value is placed before # and Keys are after # in the example file

The answer mentioned in associate multiple values for one key in array in bash couldn't be implemented. So i tried it in the following way in ksh:

#!/usr/bin/ksh

typeset -A arr

while IFS= read -r line;do
    STRIPPED=`echo $line|sed 's/.@//g'`
    OIFS="$IFS"
    IFS=','
    read -A TOKENS <<< "${STRIPPED}"
    IFS="$OIFS"

    for key in ${TOKENS[@]};do
        echo "Token is $key"    
        arr[${i##*#}]=${i%%#*}
        echo "Key: ${key##*#}, Value: ${arr[${key##*#}]}"
    done
done <MYFILE

# Printing key and its values
for i in ${!arr[@]};do
    echo "key: ${i}, value: ${arr[$i]}"
done

But this overwrites the previous values for a key. It doesnt consider multiple values for a key. Is there a way to do it in ksh(not bash)?

Answer 1

I would do this, which stores multiple values as a comma-separated string

#!/usr/bin/env ksh

# The `exec` line tells ksh to read from MYFILE _if_ stdin has _not_ been redirected
# This allows you to do:
#    ./script.ksh
#    ./script.ksh < some_other_file
#    some_process | ./script.ksh

[[ -t 0 ]] && exec 0<MYFILE

typeset -A arr

while IFS= read -r line; do
    # greatly simplified tokenization
    IFS=',' read -rA tokens <<< "${line//.*/}"

    for t in "${tokens[@]}"; do
        key=${t%#*}
        val=${t#*#}
        [[ -n ${arr[$key]} ]] && arr[$key]+=,
        arr[$key]+=$val
    done
done

# Printing key and its values
for i in "${!arr[@]}"; do
    echo "key: ${i}, value: ${arr[$i]}"
done

which outputs

key: V1, value: K1,K3
key: V2, value: K1
key: V3, value: K2

Answer 2

Assumptions:

• the input data is formatted exactly as displayed in the question (ie, no need to worry about other/extraneous text)
• line 3 of the example input is missing a '.@' on the end of the 3rd attribute/value pair
• to demonstrate duplicate processing I'll just copy the last input line a couple times
• the question has no example of the desired output so I'll use glenn's example output
• there is no explicit mention of any sorting preference (for the output) so I'll skip attempting to do any type of sorting at this point

Input file:

$ cat kdat
V1#K1.@
V2#K1.@
V3#K2.@,V4#K1.@,V5#K2.@
V1#K3.@
V1#K3.@
V1#K3.@

One solution based on sed and awk (both available in bash and ksh ) where we use the attribute/value pair as the indices of a 2-dimensional array. By assigning an arbitrary value ('1' in this case) as the array value we can eliminate duplicate values.

• the first time we see a (new) attribute/value pair we create the array element
• the next time we see the (same) attribute/value pair we simply overwrite the array element
• when we're done processing the input we find that each attribute/value pair is associated with a single array element (ie, there are no duplicates)

Now the actual code:

$ sed 's/,/\n/g;s/.@//g' kdat | awk -F"#" '
{ myarray[$1][$2]=1 }
END { for (i in myarray)
      { delim=""
        printf "key: %s, value: ",i
        for (j in myarray[i])
            { printf "%s%s",delim,j
              delim=","
            }
        printf "\n"
      }
    }
'

key: V1, value: K1,K3
key: V2, value: K1
key: V3, value: K2
key: V4, value: K1
key: V5, value: K2

Where:

• sed ... : replace comma with a carriage return (each attribute/value pair is on a separate line; this awk solution assumes one attribute/value pair per line); remove '.@'
• awk -F"#" ... : use '#' as the input delimiter for separating our attribute ($1) and value ($2) pairs
• myarray[$1][$2]=1 : create/overwrite array($1,$2) with '1'; this is where duplicates are discarded
• for / printf : loop through array indices, using printf to pretty print our output

A couple fiddles: ksh and bash