Shell Programming and Scripting

awk  '
    NR == FNR { 
    # ----------- blocks for processing file 1 ------------------------
    /^<x / {
        str = gensub(/(.+")([0-9]+)(">)(.+)(<\/.+)/, "\\2|\\4", "g")
        split( str, a, "|" );

        if( !seen[a[2]]++ )              # new group name, add it to the list
            list[++nlist] = a[2];

        agroup[group+0,a[2]] = a[1];   # changed to track across whole file

        # your original code
        B[gensub(/pattern/,"how","g")]      #Storing desired data in array B
        C[gensub(/pattern/,"how","g")]      # #Storing desired data in array C

        # small change to match D with A
        dgroup[group+0,a[2]] = gensub(/pattern/, "\\2|\\4", "g") # changed to track across whole file

        next;
    }

    /^<\/group>/ {
        group++;
        next;
    }

{
        # some other processing for file2
        if($0 == Arr1[d+1]) {Ln[d+1]=FNR;if(d<length(Arr1)-1){d++}} # Arr1 is created when processing file1
        next;
    }

    END {
        asort( list );
        for( g = 0; g < group; g++ )            # build A and D with groups seen
        {
            for( i = 1; i <= nlist; i++ )       
            {
                A[++aidx] = sprintf( "%d|%s", agroup[g,list[i]], list[i] );
                D[aidx] = dgroup[g,list[i]];
            }
        }

        # whatever end processing on A and D can be done here
        for( i = 1; i <= length( A ); i++ )         # my testing to ensure they align
            printf( "(%s) (%s)\n", A[i], D[i] );
    }
' file1 file2

oldIFS=$IFS # Default field separator in bash, IFS=" "
IFS=$'\n' # Changing temporaly to "|"
UnqGroups=( $( awk '/^<x /{print gensub(/(.+">)(.+)(<\/.+$)/,"\\2","g")}' file1 | sort -u | tr '\n' '|') )  #Unique groups
IFS=$oldIFS #Set it again to " ".

awk -v z="${UnqGroups[*]}" 'BEGIN {nlist=split(z,list,"|")-1}
    NR==FNR{    
        if($0 ~ /j v="/){
            B[gensub(/pattern/,"\\2","g")] 
            x[gensub(pattern/,"","g")];asorti(x,C) 
            
            # To generate Array A
            n=gensub(/.+="|".+$/,"","g")
            group[gensub(/pattern/,"\\2","g")]=n;
            next;
            
        }
        if($0 ~ /<\/group>/) {
        for( i = 1; i <= nlist; i++ )
            A[++w]=sprintf("%d|%s", group[list[i]], list[i] );
        delete group;   # clear for next go round
        next;} 
next}
{ 
    # code to work with file2
} 
END{ Print arrays info    }' file1 file2

FNR != NR {
    if( FNR == 1 )
          gen_array();   # only invoked on 1st record of each new file

    # rest of your code
}

awk  '
    function build(     g, i )
     {
        asort( list );
        for( g = 0; g < group; g++ )            # build A and D with groups seen
        {
            for( i = 1; i <= nlist; i++ )       # end of group, it is now safe to fill in D and A
            {
                A[++aidx] = sprintf( "%d|%s", agroup[g,list[i]], list[i] );
                D[aidx] = dgroup[g,list[i]];
            }
        }
    }

    NR != FNR {
        if( FNR == 1 )          # build the arrays when 1st record of second file is read
            build();

        # some other processing for file2
        next;
    }

    # ----------- blocks for processing file 1 ------------------------
    /^<x / {
        str = gensub(/(.+")([0-9]+)(">)(.+)(<\/.+)/, "\\2|\\4", "g")
        split( str, a, "|" );
        agroup[group+0,a[2]] = a[1];
        if( !seen[a[2]]++ )
            list[++nlist] = a[2];

        # your original code
        B[gensub(/pattern/,"how","g")]      #Storing desired data in array B
        C[gensub(/pattern/,"how","g")]      # #Storing desired data in array C

        # small change to match D with A
        dgroup[group+0,a[2]] = gensub(/pattern/, "\\2|\\4", "g") # #Storing desired data in array D

        next;
    }

    /^<\/group>/ {
        group++;
        next;
    }
' file1 file2

awk  '
    function build(     g, i )
     {
        asort( list );
        for( g = 0; g < group; g++ )            # build A and D with groups seen
        {
            for( i = 1; i <= nlist; i++ )       # end of group, it is now safe to fill in D and A
            {
                A[++aidx] = sprintf( "%d|%s", agroup[g,list[i]], list[i] );
                D[aidx] = dgroup[g,list[i]];
            }
        }
    }

 NR == FNR 
 {  # ----------- blocks for processing file 1 ------------------------
   if($0 ~ /^<x /) {
        str = gensub(/(.+")([0-9]+)(">)(.+)(<\/.+)/, "\\2|\\4", "g")
        split( str, a, "|" );
        agroup[group+0,a[2]] = a[1];
        if( !seen[a[2]]++ )
            list[++nlist] = a[2];

        # your original code
        B[gensub(/pattern/,"how","g")]      #Storing desired data in array B

        next;
    }

   if( $0 ~ /^<\/group>/) {
        group++;
        next;
    }
}

  {
        if( FNR == 1 )          # build the arrays when 1st record of second file is read
            build();

        # some other processing for file2
        next;
    }
' file1 file2