my %params = @_;

    my $mem        = (defined $params{mem} ? "-mx$params{mem}m"  : "");
    my $classifier = $params{classifier} || "weka.classifiers.rules.ZeroR ";
    my $modelfile  = $params{modelfile};
    my $testfile   = $params{testfile};
    my $predfile   = (defined $params{predfile} ? "> $params{predfile}" : "");
    my $logfile    = (defined $params{logfile} ? "> $params{logfile}" : "");

    # Execution templates (depending on whether $predfile is defined):
    # java -mx1024m weka.classifiers.trees.J48 -l J48.model -T test.arff -i > test-J48.log
    # java -mx1024m weka.classifiers.trees.J48 -l J48.model -T test.arff -i -p 0 > test-J48.pred
    my $argstr1  = "$mem $classifier -l $modelfile -T $testfile -i $logfile";
    my $argstr2  = "$mem $classifier -l $modelfile -T $testfile -i -p 0 $predfile";
    my $cpstr    = '-classpath $CLASSPATH:' . "$WEKA_JAR_PATH";
    my $test_exec_str = "java $cpstr $argstr1";
    my $pred_exec_str = "java $cpstr $argstr2";

    return (`$test_exec_str`, `$pred_exec_str`);

    my %params = @_;

    my $mem        = (defined $params{mem} ? "-mx$params{mem}m"  : "");
    my $classifier = $params{classifier};
    my $trainfile  = $params{trainfile};
    my $modelfile  = $params{modelfile};
    my $testfile   = (defined $params{testfile} ? "-T $params{testfile}" : "");
    my $logfile    = (defined $params{logfile}  ? "> $params{logfile}" : "");

    # Execution template:
    # java -mx1024m weka.classifiers.trees.J48 -t train.arff -i -k -d J48.model [-T test.arff] > train-J48.log
    my $argstr  = "$mem $classifier -t $trainfile -i -k -d $modelfile $testfile $logfile";
    my $cpstr   = '-classpath $CLASSPATH:' . "$WEKA_JAR_PATH";
    my $train_exec_str = "java $cpstr $argstr";

    return `$train_exec_str`;

    my $c       = shift;
    my $outfile = shift;
    my $header  = shift;

    open(local *FH, '>', $outfile)
      or die "write_ARFF() - unable to open $outfile for output";

	# Take relation name from cluster id, or '?' if not defined
    my $cid = $c->get_id() || "?";
    my $docsref = $c->documents();
    my %classes = $c->classes();

    #Write ARFF header
    my $header_text = $header . "\n" . '@RELATION' . " $cid\n\n";
    my $feature_text = "";

    my $attrs_declared = 0;
    foreach my $docid (sort keys %$docsref) {
        my %features = $docsref->{$docid}->get_document_features();

        my @vect = ();
		# Sort document features by feature name (to maintain same ordering each execution)
        foreach my $feature (sort keys %features) {
            my $value = $features{$feature};
			if (!ref($value)) {
				# If feature value is a scalar, can simply write it
                push @vect, $value;
                $header_text .= '@ATTRIBUTE' . " $feature NUMERIC\n" if (not $attrs_declared);
            } elsif (ref($value) eq "ARRAY") {
				# If feature value is an array, must name and treat elements as individual features
                push @vect, @$value;
                for (my $i = 1; !$attrs_declared && $i <= scalar @$value; $i++) {
                    $header_text .= '@ATTRIBUTE' . " $feature$i NUMERIC\n";
                }
            } elsif (ref($value) eq "HASH") {
				# If feature value is a hash, must flatten the hash and name and treat elements as individual features
                my $flat_hash = flatten($value);
                foreach my $key (sort keys %$flat_hash) {
                    push @vect, $flat_hash->{$key};
                    $header_text .= '@ATTRIBUTE' . " $key NUMERIC\n" if (not $attrs_declared);
                }
            } else {
				# Otherwise, not clear how to write the feature as part of an ARFF feature vector
                warn "write_ARFF() - cluster $cid: feature $feature is neither value, nor arrayref, nor hashref";
            }
        }
		# Append class label to feature vector
        $feature_text .= (join(",", (@vect, $c->get_class($docid))) . "\n");
		# Write feature vectors in buffered fashion, because feature files can be gigantic
        if (length $feature_text > $BUFFER_LEN) {
            print FH $feature_text;
            $feature_text = "";
        }

		# Prepend the ARFF header during the first buffered write of feature vectors
        if (not $attrs_declared) {
            $header_text .= '@ATTRIBUTE class {' . join(", ", sort keys %classes) . "}\n\n" . '@DATA' . "\n";
            print FH $header_text;
            $attrs_declared = 1;
        }
    }
	# Flush the buffer to write the last feature vectors
    if (length $feature_text > 0) {
        print FH $feature_text;
        $feature_text = "";
    }

    close(*FH);