Hello Perl Monks,

I am trying to solve a text parsing problem where I would like to transform the following data: 

Mon 0100
Mon 0700
Tue 0700
Wen 0100
Wen 0700
Thu 0100
Thu 0700
Fri 0100
Fri 0700
Sat 0100
Sun 0100
Sun 0700

[download]

to 

        Mon Tue Wen Thu Fri Sat Sun
0100    X       X   X   X   X   X
0700    X   X   X   X   X       X

[download]

It is basically transposing of columns where I would list the time field just once and for each day of the week found in the data, if the time existed, I would mark that column with X. If the time did not exist for that day, I would put a space.

I was able to solve the problem by doing: 

perl -lane '
    $h{$F[0]}++ or push @days, $F[0];
    $h{$F[1]}++ or push @time, $F[1];
    $data{$F[0],$F[1]}++
}{
    print "\t\t", join "\t", @days;
    for $t (@time) {
        print $t, "\t\t", join "\t", map { $data{$_,$t} ? "X" : " " } 
+@days;
    }
' file

[download]

However, I was trying to learn chaining of map function and running in to some issues. My last attempt at chaining maps is: 

perl -ane '
    $h{$F[0]}++ or push @days, $F[0];
    $h{$F[1]}++ or push @time, $F[1];
    $data{$F[0],$F[1]}++
}{
    print "\t\t", join "\t", @days;
    print "\n";
    print for join "\t", map { $t = $_ ; (map { $data{$_,$t} ? "X" : "
+ " } @days) } @time;
' file

[download]

But I am struggling to print each element of time array just once and then iterate over the hash to print X or space if the key exists.

Looking forward to your wisdom.
Regards

Jaypal

In reply to Trouble Chaining map function by jaypal

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