问将(键、值)数据转换为csv格式

EN

$ cat data.txt
  a:23 b:25 c:76 d:45
  a:21 b:24 c:25 
  a:20 d:52 e:75 f:75 g:52
  ...
  (many lines)
  ...

$ cat csv.txt
//a,b,c,d,e,f,g
23,25,76,45,0,0,0
21,24,25,0,0,0,0
20,0,0,52,75,75,52
... 
(many lines)
... 

# transform_test.pl 

# build set of all used keys.
my %usedKey;
open FILE, "data.txt";
while(<FILE>) {
        chomp $_;
        my @fields = split;
        foreach my $field (@fields) {
                my ($key,$value) = split(":",$field);
                $usedKey{$key} = 1;
        }
}
close FILE;

# build array of all used keys, but sorted.
my @sorted_keys = sort keys %usedKey;

# print header
my $header = "//";
foreach my $key (@sorted_keys) { $header .= "$key,"; }
chop $header;
print "$header\n";

# read through file again to transform the data;
open FILE, "data.txt";
while(<FILE>) {
        chomp $_;

        # build current line hash
        my @fields = split;
        my %currentData;
        foreach my $field (@fields) {
                my ($key,$value) = split(":",$field);
                $currentData{$key} = $value;
        }

        # build string by looping over all sorted keys.
        my $toPrint = "";
        foreach my $key (@sorted_keys) {
                $toPrint .= defined $currentData{$key} ? "$currentData{$key}," : "0,"; 
        }
        chop $toPrint;
        print "$toPrint\n";
}