Hi,
I am wondering about this piece of code in the get_weights_from_mert
function of mert-moses.pl:
my $sum = 0.0;
while (<$fh>) {
if (/^F(\d+) ([\-\.\de]+)/) { # regular features
$WEIGHT[$1] = $2;
$sum += abs($2);
} elsif (/^M(\d+_\d+) ([\-\.\de]+)/) { # mix weights
push @$mix_weights,$2;
} elsif (/^(.+_.+) ([\-\.\de]+)/) { # sparse features
$$sparse_weights{$1} = $2;
}
}
close $fh;
die "It seems feature values are invalid or unable to read
$outfile." if $sum < 1e-09;
$devbleu = "unknown";
foreach (@WEIGHT) { $_ /= $sum; }
foreach (keys %{$sparse_weights}) { $$sparse_weights{$_} /= $sum; }
I understand that the division by "$sum" is meant as a normalization,
but I notice that sparse features are not being summed, nevertheless
they are being normalized by the sum of the dense features. Does this
actually make sense? Also kbmira often produces several sets of weights
during one run of which only the last set is kept (the rest is being
overwritten), but the sum is collected over all sets. Looks kinda fishy :)
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