[scpubgit/stemmatology.git] / lib / Text / Tradition / Analysis.pm

package Text::Tradition::Analysis;

use strict;
use warnings;
use Benchmark;
use Exporter 'import';
use Text::Tradition;
use Text::Tradition::Stemma;

use vars qw/ @EXPORT_OK /;
@EXPORT_OK = qw/ run_analysis group_variants analyze_variant_location wit_stringify /;

sub run_analysis {
	my( $tradition ) = @_;
	# What we will return
	my $variants = [];
	my $data = {};
	
	# We need a stemma in order to run this...
	unless( $tradition->stemma_count ) {
		warn "Tradition '" . $tradition->name . "' has no stemma to analyze";
		return undef;
	}
	my $stemma = $tradition->stemma(0); # TODO allow multiple
		
	# We have the collation, so get the alignment table with witnesses in rows.
	# Also return the reading objects in the table, rather than just the words.
	my $wits = {};
	map { $wits->{$_} = 1 } $stemma->witnesses;
	# For each column in the alignment table, we want to see if the existing
	# groupings of witnesses match our stemma hypothesis. We also need to keep
	# track of the maximum number of variants at any one location.
	my $max_variants = 0;
	my ( $genealogical, $conflicts ) = ( 0, 0, 0 );
	
    my $variant_groups = group_variants( $tradition->collation, $wits );
    foreach my $rank ( 0 .. $#{$variant_groups} ) {
        my $groups = $variant_groups->[$rank]->{'groups'};
        my $readings = $variant_groups->[$rank]->{'readings'};
        my $lacunose = $variant_groups->[$rank]->{'lacunose'};
		
		$max_variants = scalar @$groups if scalar @$groups > $max_variants;
		
		# We can already look up witnesses for a reading; we also want to look
		# up readings for a given witness.
		my $group_readings = {};
		foreach my $x ( 0 .. $#$groups ) {
			$group_readings->{wit_stringify( $groups->[$x] )} = $readings->[$x];
		}
		
		# For all the groups with more than one member, collect the list of all
		# contiguous vertices needed to connect them.
		my $variant_loc = analyze_variant_location( $group_readings, $groups, 
		    $stemma->graph, $lacunose );
		$variant_loc->{'id'} = $rank;
		$genealogical++ if $variant_loc->{'genealogical'};
		$conflicts += grep { $_->{'conflict'} } @{$variant_loc->{'readings'}};

		# Now run the same analysis given the calculated distance tree(s).
# 		my @trees = @{$stemma->distance_trees};
# 		if( @trees ) {
#             foreach my $tree ( 0 .. $#trees ) {
#                 my $dc = analyze_variant_location( $group_readings, $groups, $tree, $lacunose, 'undirected' );
#                 foreach my $rdg ( keys %$dc ) {
#                     my $var = $dc->{$rdg};
#                     # TODO Do something with this
#                 }
#             }
# 	    }

		# Record that we used this variant in an analysis
		push( @$variants, $variant_loc );
	}

	# Go through our variant locations, after we have seen all of them once,
	# and add the number of empty columns needed by each.
	foreach my $row ( @$variants ) {
		my $empty = $max_variants - scalar @{$row->{'readings'}};
		$row->{'empty'} = $empty;
	}
	
	$data->{'variants'} = $variants;
	$data->{'variant_count'} = $tradition->collation->end->rank - 1;
	$data->{'conflict_count'} = $conflicts;
	$data->{'genealogical_count'} = $genealogical;
	return $data;
}

sub group_variants {
	my( $c, $wits ) = @_;
	my $variant_groups = [];
	
	# We have the collation, so get the alignment table with witnesses in rows.
	# Also return the reading objects in the table, rather than just the words.
	my $all_wits_table = $c->make_alignment_table( 'refs', $wits );
	# Strip the list of sigla and save it for correlation to the readings.
	my @table_wits = map { $_->{'witness'} } @{$all_wits_table->{'alignment'}};
	# Any witness in the stemma that has no row should be noted.
    foreach ( @table_wits ) {
        $wits->{$_}++; # Witnesses present in table and stemma now have value 2.
    }
    my @not_collated = grep { $wits->{$_} == 1 } keys %$wits;
	foreach my $i ( 0 .. $all_wits_table->{'length'} - 1 ) {
		# For each column in the table, group the readings by witness.
		my $rdg_wits = {};
		my @col_rdgs = map { $_->{tokens}->[$i] } @{$all_wits_table->{'alignment'}};
		my $lacunose = [ @not_collated ];
		foreach my $j ( 0 .. $#col_rdgs ) {
			my $rdg = $col_rdgs[$j];
			my $rdg_text = '(omitted)';  # Initialize in case of empty reading
			if( $rdg ) {
			    if( $rdg->{'t'}->is_lacuna ) {
			        $rdg_text = undef;   # Don't count lacunae
			        push( @$lacunose, $table_wits[$j] );
			    } else {
    				$rdg_text = $rdg->{'t'}->text; 
				}
			}
			if( defined $rdg_text ) {
				# Initialize the witness array if we haven't got one yet
				$rdg_wits->{$rdg_text} = [] unless $rdg_wits->{$rdg_text};
				# Add the relevant witness, subject to a.c. logic
				add_variant_wit( $rdg_wits->{$rdg_text}, $table_wits[$j],
					$c->ac_label );
			}
		}
		
		# See if this column has any potentially genealogical variants.
		# If not, skip to the next.
		my( $groups, $readings ) = useful_variant( $rdg_wits );
		next unless $groups && $readings;  

		push( @$variant_groups, 
		    { 'groups' => $groups, 'readings' => $readings, 'lacunose' => $lacunose } );
	}
	return $variant_groups;
}


# variant_row -> genealogical
#             -> readings [ { text, group, conflict, missing } ]

sub analyze_variant_location {
    my( $group_readings, $groups, $graph, $lacunose, $undirected ) = @_;
    my $contig = {};
    my $subgraph = {};
    my $is_conflicted;
    my $conflict = {};
    my $missing = {};
    map { $missing->{$_} = 1 } @$lacunose;
    my $variant_row = { 'readings' => [] };
    # Mark each ms as in its own group, first.
    foreach my $g ( @$groups ) {
        my $gst = wit_stringify( $g );
        map { $contig->{$_} = $gst } @$g;
    }
    # Now for each unmarked node in the graph, initialize an array
    # for possible group memberships.  We will use this later to
    # resolve potential conflicts.
    map { $contig->{$_} = [] unless $contig->{$_} } $graph->vertices;
    foreach my $g ( sort { scalar @$b <=> scalar @$a } @$groups ) {
        my $gst = wit_stringify( $g );  # This is the group name
        my $reachable = { $g->[0] => 1 };
        # Copy the graph, and delete all non-members from the new graph.
        my $part = $graph->copy;
        my $group_root;
        $part->delete_vertices( 
            grep { !ref( $contig->{$_} ) && $contig->{$_} ne $gst } $graph->vertices );
                
        # Now look to see if our group is connected.
        if( $undirected ) { # For use with distance trees etc.
            # Find all vertices reachable from the first (arbitrary) group
            # member.  If we are genealogical this should include them all. 
            map { $reachable->{$_} = 1 } $part->all_reachable( $g->[0] );
            # TODO This is a terrible way to do distance trees, since all
            # non-leaf nodes are included in every graph part now. We may
            # have to go back to SPDP.
        } else {
            if( @$g > 1 ) {
                # Dispense with the trivial case of one reading.
                # We have to take directionality into account.
                # How many root nodes do we have?
                my @roots = grep { ref( $contig->{$_} ) || $contig->{$_} eq $gst } 
                    $part->source_vertices;
                # Assuming that @$g > 1, find the first root node that has at
                # least one successor belonging to our group. If this reading
                # is genealogical, there should be only one, but we will check
                # that implicitly later.
                my $nodes_in_subtree = 0;
                foreach my $root ( @roots ) {
                    # Prune the tree to get rid of extraneous hypotheticals.
                    $root = prune_subtree( $part, $root, $contig );
                    # Get all the successor nodes of our root.
                    my $tmp_reach = { $root => 1 };
                    map { $tmp_reach->{$_} = 1 } $part->all_successors( $root );
                    # Skip this root if none of our successors are in our group
                    # (e.g. isolated 'hypothetical' witnesses with no group)
                    next unless grep { $contig->{$_} } keys %$tmp_reach;
                    if( keys %$tmp_reach > $nodes_in_subtree ) {
                        $nodes_in_subtree = keys %$tmp_reach;
                        $reachable = $tmp_reach;
                        $group_root = $root;
                    }
                }
            } # else it is a single-node group, nothing to calculate.
        }
        
        # None of the 'reachable' nodes should be marked as being in another 
        # group.  Paint the 'hypotheticals' with our group while we are at it,
        # unless there is a conflict present.
        foreach ( keys %$reachable ) {
            if( ref $contig->{$_} ) {
                push( @{$contig->{$_}}, $gst );
            } elsif( $contig->{$_} ne $gst ) {
                $conflict->{$group_readings->{$gst}} = $group_readings->{$contig->{$_}};
            } # else it is an 'extant' node marked with our group already.
        }
        # None of the unreachable nodes should be in our group either.
        foreach ( $part->vertices ) {
            next if $reachable->{$_};
            if( $contig->{$_} eq $gst ) {
                $conflict->{$group_readings->{$gst}} = $group_readings->{$gst};
                last;
            }
        }
        
        # Now, if we have a conflict, we can write the reading in full.  If not, 
        # we have to save the subgraph so that we can resolve possible conflicts 
        # on hypothetical nodes.
        $is_conflicted = 1 if exists $conflict->{$group_readings->{$gst}};
        
        # Write the reading.
        my $reading = { 'text' => $group_readings->{$gst},
                        'missing' => wit_stringify( $lacunose ),
                        'group' => $gst };  # This will change if we find no conflict
        if( $is_conflicted ) {
            $reading->{'conflict'} = $conflict->{$group_readings->{$gst}}
        } else {
            # Save the relevant subgraph.
            $subgraph->{$gst} = { 'graph' => $part,
                                'root' => $group_root,
                                'reachable' => $reachable };
        }
        push( @{$variant_row->{'readings'}}, $reading );
    }
    
    # Now that we have gone through all the rows, check the hypothetical
    # readings for conflict if we haven't found one yet.
    if( keys %$subgraph && !keys %$conflict ) {
        my @resolve;
        foreach ( keys %$contig ) {
            next unless ref $contig->{$_};
            if( scalar @{$contig->{$_}} > 1 ) {
                push( @resolve, $_ );
            } else {
                $contig->{$_} = scalar @{$contig->{$_}} ? $contig->{$_}->[0] : '';
            }
        }
        # Do we still have a possible conflict?
        my $still_contig = {};
        foreach my $h ( @resolve ) {
            # For each of the hypothetical readings with more than one possibility,
            # try deleting it from each of its member subgraphs in turn, and see
            # if that breaks the contiguous grouping.
            # TODO This can still break in a corner case where group A can use 
            # either vertex 1 or 2, and group B can use either vertex 2 or 1.
            # Revisit this if necessary; it could get brute-force nasty.
            foreach my $gst ( @{$contig->{$h}} ) {
                my $gpart = $subgraph->{$gst}->{'graph'}->copy;
                my $reachable = $subgraph->{$gst}->{'reachable'};
                $gpart->delete_vertex( $h );
                # Is everything else still reachable from the root?
                # TODO If $h was the root, see if we still have a single root.
                my %still_reachable = ( $subgraph->{$gst}->{'root'} => 1 );
                map { $still_reachable{$_} = 1 }
                    $gpart->all_successors( $subgraph->{$gst}->{'root'} );
                foreach my $v ( keys %$reachable ) {
                    next if $v eq $h;
                    if( !$still_reachable{$v}
                        && ( $contig->{$v} eq $gst 
                             || ( exists $still_contig->{$v} 
                                  && $still_contig->{$v} eq $gst ) ) ) {
                        # We need $h.
                        if( exists $still_contig->{$h} ) {
                            # Conflict!
                            $conflict->{$group_readings->{$gst}} = 
                                $group_readings->{$still_contig->{$h}};
                        } else {
                            $still_contig->{$h} = $gst;
                        }
                        last;
                    } # else we don't need $h in this group.
                }
            }
        }
        
        # Now, assuming no conflict, we have some hypothetical vertices in
        # $still_contig that are the "real" group memberships.  Replace these
        # in $contig.
        unless ( keys %$conflict ) {
            foreach my $v ( keys %$contig ) {
                next unless ref $contig->{$v};
                $contig->{$v} = $still_contig->{$v};
            }
        }
    }
            
    # Now write the group and conflict information into the respective rows.
    foreach my $rdg ( @{$variant_row->{'readings'}} ) {
        $rdg->{'conflict'} = $conflict->{$rdg->{'text'}};
        next if $rdg->{'conflict'};
        my @members = grep { $contig->{$_} eq $rdg->{'group'} && !$missing->{$_} } 
            keys %$contig;
        $rdg->{'group'} = wit_stringify( \@members );
    }
    
    $variant_row->{'genealogical'} = !( keys %$conflict );
    return $variant_row;
}

sub prune_subtree {
    my( $tree, $root, $contighash ) = @_;
    # First, delete hypothetical leaves / orphans until there are none left.
    my @orphan_hypotheticals = grep { ref( $contighash->{$_} ) } 
        $tree->successorless_vertices;
    while( @orphan_hypotheticals ) {
        $tree->delete_vertices( @orphan_hypotheticals );
        @orphan_hypotheticals = grep { ref( $contighash->{$_} ) } 
            $tree->successorless_vertices;
    }
    # Then delete a hypothetical root with only one successor, moving the
    # root to the child.
    while( $tree->successors( $root ) == 1 && ref $contighash->{$root} ) {
        my @nextroot = $tree->successors( $root );
        $tree->delete_vertex( $root );
        $root = $nextroot[0];
    }
    # The tree has been modified in place, but we need to know the new root.
    return $root;
}
# Add the variant, subject to a.c. representation logic.
# This assumes that we will see the 'main' version before the a.c. version.
sub add_variant_wit {
    my( $arr, $wit, $acstr ) = @_;
    my $skip;
    if( $wit =~ /^(.*)\Q$acstr\E$/ ) {
        my $real = $1;
        $skip = grep { $_ =~ /^\Q$real\E$/ } @$arr;
    } 
    push( @$arr, $wit ) unless $skip;
}

# Return an answer if the variant is useful, i.e. if there are at least 2 variants
# with at least 2 witnesses each.
sub useful_variant {
    my( $readings ) = @_;
    my $total = keys %$readings;
    foreach my $var ( keys %$readings ) {
        $total-- if @{$readings->{$var}} == 1;
    }
    return( undef, undef ) if $total <= 1;
    my( $groups, $text );
    foreach my $var ( keys %$readings ) {
        push( @$groups, $readings->{$var} );
        push( @$text, $var );
    }
    return( $groups, $text );
}

# Take an array of witness groupings and produce a string like
# ['A','B'] / ['C','D','E'] / ['F']

sub wit_stringify {
    my $groups = shift;
    my @gst;
    # If we were passed an array of witnesses instead of an array of 
    # groupings, then "group" the witnesses first.
    unless( ref( $groups->[0] ) ) {
        my $mkgrp = [ $groups ];
        $groups = $mkgrp;
    }
    foreach my $g ( @$groups ) {
        push( @gst, '[' . join( ',', map { "'$_'" } @$g ) . ']' );
    }
    return join( ' / ', @gst );
}
    
1;
Commit	Line	Data
d71100ed	1	package Text::Tradition::Analysis;
	2
	3	use strict;
	4	use warnings;
e4386ba9	5	use Benchmark;
d1348d38	6	use Exporter 'import';
d71100ed	7	use Text::Tradition;
	8	use Text::Tradition::Stemma;
	9
d1348d38	10	use vars qw/ @EXPORT_OK /;
a2cf85dd	11	@EXPORT_OK = qw/ run_analysis group_variants analyze_variant_location wit_stringify /;
d1348d38	12
d71100ed	13	sub run_analysis {
56cf65bd	14	my( $tradition ) = @_;
d71100ed	15	# What we will return
d71100ed	16	my $variants = [];
e367f5c0	17	my $data = {};
56cf65bd	18
56cf65bd	19	# We need a stemma in order to run this...
b979e2e2	20	unless( $tradition->stemma_count ) {
56cf65bd	21	warn "Tradition '" . $tradition->name . "' has no stemma to analyze";
	22	return undef;
	23	}
b979e2e2	24	my $stemma = $tradition->stemma(0); # TODO allow multiple
3837c155	25
d71100ed	26	# We have the collation, so get the alignment table with witnesses in rows.
d71100ed	27	# Also return the reading objects in the table, rather than just the words.
08e0fb85	28	my $wits = {};
08e0fb85	29	map { $wits->{$_} = 1 } $stemma->witnesses;
d71100ed	30	# For each column in the alignment table, we want to see if the existing
f6c8ea08	31	# groupings of witnesses match our stemma hypothesis. We also need to keep
	32	# track of the maximum number of variants at any one location.
	33	my $max_variants = 0;
a2cf85dd	34	my ( $genealogical, $conflicts ) = ( 0, 0, 0 );
d71100ed	35
f6c8ea08	36	my $variant_groups = group_variants( $tradition->collation, $wits );
	37	foreach my $rank ( 0 .. $#{$variant_groups} ) {
	38	my $groups = $variant_groups->[$rank]->{'groups'};
	39	my $readings = $variant_groups->[$rank]->{'readings'};
	40	my $lacunose = $variant_groups->[$rank]->{'lacunose'};
d71100ed	41
f6c8ea08	42	$max_variants = scalar @$groups if scalar @$groups > $max_variants;
d71100ed	43
	44	# We can already look up witnesses for a reading; we also want to look
	45	# up readings for a given witness.
	46	my $group_readings = {};
	47	foreach my $x ( 0 .. $#$groups ) {
	48	$group_readings->{wit_stringify( $groups->[$x] )} = $readings->[$x];
	49	}
	50
	51	# For all the groups with more than one member, collect the list of all
	52	# contiguous vertices needed to connect them.
f6c8ea08	53	my $variant_loc = analyze_variant_location( $group_readings, $groups,
08e0fb85	54	$stemma->graph, $lacunose );
f6c8ea08	55	$variant_loc->{'id'} = $rank;
	56	$genealogical++ if $variant_loc->{'genealogical'};
	57	$conflicts += grep { $_->{'conflict'} } @{$variant_loc->{'readings'}};
732152b1	58
d71100ed	59	# Now run the same analysis given the calculated distance tree(s).
732152b1	60	# my @trees = @{$stemma->distance_trees};
	61	# if( @trees ) {
	62	# foreach my $tree ( 0 .. $#trees ) {
c4a4fb1b	63	# my $dc = analyze_variant_location( $group_readings, $groups, $tree, $lacunose, 'undirected' );
732152b1	64	# foreach my $rdg ( keys %$dc ) {
	65	# my $var = $dc->{$rdg};
	66	# # TODO Do something with this
	67	# }
	68	# }
	69	# }
	70
d71100ed	71	# Record that we used this variant in an analysis
f6c8ea08	72	push( @$variants, $variant_loc );
d71100ed	73	}
a2cf85dd	74
f6c8ea08	75	# Go through our variant locations, after we have seen all of them once,
732152b1	76	# and add the number of empty columns needed by each.
d71100ed	77	foreach my $row ( @$variants ) {
f6c8ea08	78	my $empty = $max_variants - scalar @{$row->{'readings'}};
d71100ed	79	$row->{'empty'} = $empty;
	80	}
	81
e367f5c0	82	$data->{'variants'} = $variants;
a2cf85dd	83	$data->{'variant_count'} = $tradition->collation->end->rank - 1;
e367f5c0	84	$data->{'conflict_count'} = $conflicts;
e367f5c0	85	$data->{'genealogical_count'} = $genealogical;
3837c155	86	return $data;
d71100ed	87	}
d71100ed	88
d1348d38	89	sub group_variants {
	90	my( $c, $wits ) = @_;
	91	my $variant_groups = [];
	92
f6c8ea08	93	# We have the collation, so get the alignment table with witnesses in rows.
f6c8ea08	94	# Also return the reading objects in the table, rather than just the words.
d1348d38	95	my $all_wits_table = $c->make_alignment_table( 'refs', $wits );
d1348d38	96	# Strip the list of sigla and save it for correlation to the readings.
b5c47c25	97	my @table_wits = map { $_->{'witness'} } @{$all_wits_table->{'alignment'}};
d1348d38	98	# Any witness in the stemma that has no row should be noted.
b5c47c25	99	foreach ( @table_wits ) {
d1348d38	100	$wits->{$_}++; # Witnesses present in table and stemma now have value 2.
d1348d38	101	}
f6c8ea08	102	my @not_collated = grep { $wits->{$_} == 1 } keys %$wits;
b5c47c25	103	foreach my $i ( 0 .. $all_wits_table->{'length'} - 1 ) {
d1348d38	104	# For each column in the table, group the readings by witness.
d1348d38	105	my $rdg_wits = {};
b5c47c25	106	my @col_rdgs = map { $_->{tokens}->[$i] } @{$all_wits_table->{'alignment'}};
d1348d38	107	my $lacunose = [ @not_collated ];
b5c47c25	108	foreach my $j ( 0 .. $#col_rdgs ) {
b5c47c25	109	my $rdg = $col_rdgs[$j];
d1348d38	110	my $rdg_text = '(omitted)'; # Initialize in case of empty reading
d1348d38	111	if( $rdg ) {
b5c47c25	112	if( $rdg->{'t'}->is_lacuna ) {
d1348d38	113	$rdg_text = undef; # Don't count lacunae
b5c47c25	114	push( @$lacunose, $table_wits[$j] );
d1348d38	115	} else {
b5c47c25	116	$rdg_text = $rdg->{'t'}->text;
d1348d38	117	}
	118	}
	119	if( defined $rdg_text ) {
	120	# Initialize the witness array if we haven't got one yet
	121	$rdg_wits->{$rdg_text} = [] unless $rdg_wits->{$rdg_text};
	122	# Add the relevant witness, subject to a.c. logic
b5c47c25	123	add_variant_wit( $rdg_wits->{$rdg_text}, $table_wits[$j],
d1348d38	124	$c->ac_label );
	125	}
	126	}
	127
	128	# See if this column has any potentially genealogical variants.
	129	# If not, skip to the next.
	130	my( $groups, $readings ) = useful_variant( $rdg_wits );
	131	next unless $groups && $readings;
	132
f6c8ea08	133	push( @$variant_groups,
f6c8ea08	134	{ 'groups' => $groups, 'readings' => $readings, 'lacunose' => $lacunose } );
d1348d38	135	}
	136	return $variant_groups;
	137	}
	138
f6c8ea08	139
f6c8ea08	140
732152b1	141	# variant_row -> genealogical
	142	# -> readings [ { text, group, conflict, missing } ]
	143
d71100ed	144	sub analyze_variant_location {
c4a4fb1b	145	my( $group_readings, $groups, $graph, $lacunose, $undirected ) = @_;
231d71fc	146	my $contig = {};
231d71fc	147	my $subgraph = {};
c4a4fb1b	148	my $is_conflicted;
d71100ed	149	my $conflict = {};
231d71fc	150	my $missing = {};
231d71fc	151	map { $missing->{$_} = 1 } @$lacunose;
732152b1	152	my $variant_row = { 'readings' => [] };
94a077d6	153	# Mark each ms as in its own group, first.
	154	foreach my $g ( @$groups ) {
	155	my $gst = wit_stringify( $g );
231d71fc	156	map { $contig->{$_} = $gst } @$g;
94a077d6	157	}
c4a4fb1b	158	# Now for each unmarked node in the graph, initialize an array
	159	# for possible group memberships. We will use this later to
	160	# resolve potential conflicts.
231d71fc	161	map { $contig->{$_} = [] unless $contig->{$_} } $graph->vertices;
d71100ed	162	foreach my $g ( sort { scalar @$b <=> scalar @$a } @$groups ) {
c4a4fb1b	163	my $gst = wit_stringify( $g ); # This is the group name
c4a4fb1b	164	my $reachable = { $g->[0] => 1 };
08e0fb85	165	# Copy the graph, and delete all non-members from the new graph.
c4a4fb1b	166	my $part = $graph->copy;
	167	my $group_root;
	168	$part->delete_vertices(
231d71fc	169	grep { !ref( $contig->{$_} ) && $contig->{$_} ne $gst } $graph->vertices );
c4a4fb1b	170
	171	# Now look to see if our group is connected.
	172	if( $undirected ) { # For use with distance trees etc.
	173	# Find all vertices reachable from the first (arbitrary) group
	174	# member. If we are genealogical this should include them all.
	175	map { $reachable->{$_} = 1 } $part->all_reachable( $g->[0] );
	176	# TODO This is a terrible way to do distance trees, since all
	177	# non-leaf nodes are included in every graph part now. We may
	178	# have to go back to SPDP.
	179	} else {
	180	if( @$g > 1 ) {
	181	# Dispense with the trivial case of one reading.
	182	# We have to take directionality into account.
	183	# How many root nodes do we have?
231d71fc	184	my @roots = grep { ref( $contig->{$_} ) \|\| $contig->{$_} eq $gst }
c4a4fb1b	185	$part->source_vertices;
	186	# Assuming that @$g > 1, find the first root node that has at
	187	# least one successor belonging to our group. If this reading
	188	# is genealogical, there should be only one, but we will check
	189	# that implicitly later.
	190	my $nodes_in_subtree = 0;
	191	foreach my $root ( @roots ) {
231d71fc	192	# Prune the tree to get rid of extraneous hypotheticals.
231d71fc	193	$root = prune_subtree( $part, $root, $contig );
c4a4fb1b	194	# Get all the successor nodes of our root.
	195	my $tmp_reach = { $root => 1 };
	196	map { $tmp_reach->{$_} = 1 } $part->all_successors( $root );
	197	# Skip this root if none of our successors are in our group
	198	# (e.g. isolated 'hypothetical' witnesses with no group)
231d71fc	199	next unless grep { $contig->{$_} } keys %$tmp_reach;
c4a4fb1b	200	if( keys %$tmp_reach > $nodes_in_subtree ) {
	201	$nodes_in_subtree = keys %$tmp_reach;
	202	$reachable = $tmp_reach;
	203	$group_root = $root;
	204	}
	205	}
	206	} # else it is a single-node group, nothing to calculate.
	207	}
	208
	209	# None of the 'reachable' nodes should be marked as being in another
	210	# group. Paint the 'hypotheticals' with our group while we are at it,
	211	# unless there is a conflict present.
	212	foreach ( keys %$reachable ) {
231d71fc	213	if( ref $contig->{$_} ) {
	214	push( @{$contig->{$_}}, $gst );
	215	} elsif( $contig->{$_} ne $gst ) {
	216	$conflict->{$group_readings->{$gst}} = $group_readings->{$contig->{$_}};
c4a4fb1b	217	} # else it is an 'extant' node marked with our group already.
d71100ed	218	}
08e0fb85	219	# None of the unreachable nodes should be in our group either.
08e0fb85	220	foreach ( $part->vertices ) {
c4a4fb1b	221	next if $reachable->{$_};
231d71fc	222	if( $contig->{$_} eq $gst ) {
c4a4fb1b	223	$conflict->{$group_readings->{$gst}} = $group_readings->{$gst};
	224	last;
	225	}
08e0fb85	226	}
08e0fb85	227
c4a4fb1b	228	# Now, if we have a conflict, we can write the reading in full. If not,
	229	# we have to save the subgraph so that we can resolve possible conflicts
	230	# on hypothetical nodes.
	231	$is_conflicted = 1 if exists $conflict->{$group_readings->{$gst}};
	232
732152b1	233	# Write the reading.
	234	my $reading = { 'text' => $group_readings->{$gst},
	235	'missing' => wit_stringify( $lacunose ),
c4a4fb1b	236	'group' => $gst }; # This will change if we find no conflict
	237	if( $is_conflicted ) {
	238	$reading->{'conflict'} = $conflict->{$group_readings->{$gst}}
732152b1	239	} else {
c4a4fb1b	240	# Save the relevant subgraph.
231d71fc	241	$subgraph->{$gst} = { 'graph' => $part,
c4a4fb1b	242	'root' => $group_root,
c4a4fb1b	243	'reachable' => $reachable };
732152b1	244	}
732152b1	245	push( @{$variant_row->{'readings'}}, $reading );
d71100ed	246	}
c4a4fb1b	247
	248	# Now that we have gone through all the rows, check the hypothetical
	249	# readings for conflict if we haven't found one yet.
231d71fc	250	if( keys %$subgraph && !keys %$conflict ) {
c4a4fb1b	251	my @resolve;
231d71fc	252	foreach ( keys %$contig ) {
	253	next unless ref $contig->{$_};
	254	if( scalar @{$contig->{$_}} > 1 ) {
c4a4fb1b	255	push( @resolve, $_ );
c4a4fb1b	256	} else {
231d71fc	257	$contig->{$_} = scalar @{$contig->{$_}} ? $contig->{$_}->[0] : '';
c4a4fb1b	258	}
	259	}
	260	# Do we still have a possible conflict?
231d71fc	261	my $still_contig = {};
c4a4fb1b	262	foreach my $h ( @resolve ) {
	263	# For each of the hypothetical readings with more than one possibility,
	264	# try deleting it from each of its member subgraphs in turn, and see
	265	# if that breaks the contiguous grouping.
	266	# TODO This can still break in a corner case where group A can use
	267	# either vertex 1 or 2, and group B can use either vertex 2 or 1.
	268	# Revisit this if necessary; it could get brute-force nasty.
231d71fc	269	foreach my $gst ( @{$contig->{$h}} ) {
	270	my $gpart = $subgraph->{$gst}->{'graph'}->copy;
	271	my $reachable = $subgraph->{$gst}->{'reachable'};
c4a4fb1b	272	$gpart->delete_vertex( $h );
	273	# Is everything else still reachable from the root?
	274	# TODO If $h was the root, see if we still have a single root.
231d71fc	275	my %still_reachable = ( $subgraph->{$gst}->{'root'} => 1 );
c4a4fb1b	276	map { $still_reachable{$_} = 1 }
231d71fc	277	$gpart->all_successors( $subgraph->{$gst}->{'root'} );
c4a4fb1b	278	foreach my $v ( keys %$reachable ) {
	279	next if $v eq $h;
	280	if( !$still_reachable{$v}
231d71fc	281	&& ( $contig->{$v} eq $gst
	282	\|\| ( exists $still_contig->{$v}
	283	&& $still_contig->{$v} eq $gst ) ) ) {
c4a4fb1b	284	# We need $h.
231d71fc	285	if( exists $still_contig->{$h} ) {
c4a4fb1b	286	# Conflict!
c4a4fb1b	287	$conflict->{$group_readings->{$gst}} =
231d71fc	288	$group_readings->{$still_contig->{$h}};
c4a4fb1b	289	} else {
231d71fc	290	$still_contig->{$h} = $gst;
c4a4fb1b	291	}
	292	last;
	293	} # else we don't need $h in this group.
	294	}
	295	}
	296	}
	297
	298	# Now, assuming no conflict, we have some hypothetical vertices in
	299	# $still_contig that are the "real" group memberships. Replace these
	300	# in $contig.
	301	unless ( keys %$conflict ) {
231d71fc	302	foreach my $v ( keys %$contig ) {
	303	next unless ref $contig->{$v};
	304	$contig->{$v} = $still_contig->{$v};
c4a4fb1b	305	}
	306	}
	307	}
	308
	309	# Now write the group and conflict information into the respective rows.
	310	foreach my $rdg ( @{$variant_row->{'readings'}} ) {
	311	$rdg->{'conflict'} = $conflict->{$rdg->{'text'}};
	312	next if $rdg->{'conflict'};
231d71fc	313	my @members = grep { $contig->{$_} eq $rdg->{'group'} && !$missing->{$_} }
231d71fc	314	keys %$contig;
c4a4fb1b	315	$rdg->{'group'} = wit_stringify( \@members );
	316	}
	317
08e0fb85	318	$variant_row->{'genealogical'} = !( keys %$conflict );
732152b1	319	return $variant_row;
d71100ed	320	}
d71100ed	321
231d71fc	322	sub prune_subtree {
	323	my( $tree, $root, $contighash ) = @_;
	324	# First, delete hypothetical leaves / orphans until there are none left.
	325	my @orphan_hypotheticals = grep { ref( $contighash->{$_} ) }
	326	$tree->successorless_vertices;
	327	while( @orphan_hypotheticals ) {
	328	$tree->delete_vertices( @orphan_hypotheticals );
	329	@orphan_hypotheticals = grep { ref( $contighash->{$_} ) }
	330	$tree->successorless_vertices;
	331	}
	332	# Then delete a hypothetical root with only one successor, moving the
	333	# root to the child.
	334	while( $tree->successors( $root ) == 1 && ref $contighash->{$root} ) {
	335	my @nextroot = $tree->successors( $root );
	336	$tree->delete_vertex( $root );
	337	$root = $nextroot[0];
	338	}
	339	# The tree has been modified in place, but we need to know the new root.
	340	return $root;
	341	}
d71100ed	342	# Add the variant, subject to a.c. representation logic.
	343	# This assumes that we will see the 'main' version before the a.c. version.
	344	sub add_variant_wit {
	345	my( $arr, $wit, $acstr ) = @_;
	346	my $skip;
	347	if( $wit =~ /^(.*)\Q$acstr\E$/ ) {
	348	my $real = $1;
	349	$skip = grep { $_ =~ /^\Q$real\E$/ } @$arr;
	350	}
	351	push( @$arr, $wit ) unless $skip;
	352	}
	353
	354	# Return an answer if the variant is useful, i.e. if there are at least 2 variants
	355	# with at least 2 witnesses each.
	356	sub useful_variant {
	357	my( $readings ) = @_;
	358	my $total = keys %$readings;
	359	foreach my $var ( keys %$readings ) {
	360	$total-- if @{$readings->{$var}} == 1;
	361	}
	362	return( undef, undef ) if $total <= 1;
	363	my( $groups, $text );
	364	foreach my $var ( keys %$readings ) {
	365	push( @$groups, $readings->{$var} );
	366	push( @$text, $var );
	367	}
	368	return( $groups, $text );
	369	}
	370
	371	# Take an array of witness groupings and produce a string like
	372	# ['A','B'] / ['C','D','E'] / ['F']
	373
	374	sub wit_stringify {
	375	my $groups = shift;
	376	my @gst;
	377	# If we were passed an array of witnesses instead of an array of
	378	# groupings, then "group" the witnesses first.
	379	unless( ref( $groups->[0] ) ) {
	380	my $mkgrp = [ $groups ];
	381	$groups = $mkgrp;
	382	}
	383	foreach my $g ( @$groups ) {
	384	push( @gst, '[' . join( ',', map { "'$_'" } @$g ) . ']' );
	385	}
	386	return join( ' / ', @gst );
	387	}
	388
	389	1;