Perl输出哈希数组作为表

Question

如果你有一个哈希数组，其中键表示列名，值是行内容，那么在perl中输出它作为表的最佳方法是什么？

Answer 1

Does each row have the same hash keys? That's the structure you would get, eg from DBI, corresponding to the generally understood properties of tables (ie each row has the same set of columns). Here's a sample of what I have in mind, and I hope it matches what you're thinking:

my @AoH = (
    {id => 1, name => 'Dick'},
    {id => 2, name => 'Jane'},
);

In such cases you normally know what the columns are. I'm going to make that assumption. Here, then, is the code:

my @cols = qw(id name);
my @AoH;                 # as above

# print the column headings
print join "\t", @cols;

# print values for each row using a hash slice
for my $row_ref (@AoH) {
    print join "\t", @$row_ref{@cols};
}

Answer 2

Like this?

my @AoH = (
    {a => 1, b => 2},
    {c => 3, d => 4},
);

This maps to an N-dimensional table, where N is the number of elements in the array. You can't really visualize it for more than N = 3, unless you collapse the hashes (ie, make it all one big hash.)

If you just mean tabulate a 'reversed' hash, just transpose it:

my %a = (a => 1, b => 1);

my %b = map { $a{$_} => $_ } keys %a;

while ( my ($k, $v) = each %b ) {
    printf( "%s %s\n", $k, $v );
}