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yap-6.3/CLPBN/clpbn/viterbi.yap
vsc cffa76355e More viterbi fixes
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1368 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2005-08-19 03:38:08 +00:00

178 lines
4.2 KiB
Prolog

:- style_check(all).
:- module(viterbi, [viterbi/3]).
:- use_module(library(lists),
[nth/3]).
:- use_module(library('clpbn'), []).
:- use_module(library('clpbn/utils'), [
sort_vars_by_key_and_parents/3]).
:- use_module(library('ugraphs'), [
vertices_edges_to_ugraph/3,
add_edges/3,
top_sort/3]).
:- attribute prob/1, emission/1, backp/1.
viterbi(Start,End,Trace) :-
attributes:all_attvars(Vars0),
sort_vars_by_key_and_parents(Vars0,Vars,_),
add_emissions(Vars),
topsort_vars(Vars,SortedVars),
init_viterbi(Start),
viterbi_alg(SortedVars),
backtrace(Start,End,[],Trace).
add_emissions([]).
add_emissions([Var|Vars]) :-
add_emission(Var),
add_emissions(Vars).
add_emission(Var) :-
clpbn:get_atts(Var,[key(K),evidence(Ev),dist(Vals,emission(CPT),Parents)]), !,
cvt_vals(Vals,LVals),
once(nth(Nth, LVals, Ev)),
find_probs(CPT,K,Nth,Prob),
adde2pars(Parents,Prob).
add_emission(_).
%
% well known domains
%
cvt_vals(aminoacids,[a, c, d, e, f, g, h, i, k, l, m, n, p, q, r, s, t, v, w, y]).
cvt_vals(bool,[t,f]).
cvt_vals(bases,[a,c,g,t]).
cvt_vals([A|B],[A|B]).
% first, try standard representation
find_probs(Logs,_,Nth,Log) :-
compound(Logs),
arg(Nth,Logs,Log), !.
% key independent, compacted
find_probs(A,_,Nth,Log) :- atom(A), !,
user:compacted_cpt(A,Logs),
arg(Nth,Logs,Log).
% key dependent, compacted
find_probs(I,K,Nth,Log) :- integer(I), !,
functor(K,A,_),
user:compacted_cpt(A,I,Logs),
arg(Nth,Logs,Log).
% now, try hacked representation
% get_norm(Norms,Nth,Norm).
%get_norm(Norms,_,Norms) :- number(Norms), !.
%get_norm(Norms,Nth,Norm) :-
% arg(Nth,Norms,Norm).
adde2pars([],_).
adde2pars([V|Vs],P) :-
put_atts(V,[emission(P)]),
adde2pars(Vs,P).
topsort_vars(Vars,SortedVars) :-
vertices_edges_to_ugraph([],[],Graph0),
sort_vars(Vars, Graph0, SortedVars).
%
% take advantage of the fact that variables can be split by timestamp.
%
sort_vars(Vars, Graph0, SortedVars) :-
fetch_times(Vars,T0Vars),
keysort(T0Vars, TVars),
sort_times(TVars, Graph0, SortedVars).
fetch_times([], []).
fetch_times([V|Vs], [T-V|TVs]) :-
clpbn:get_atts(V,[key(K)]),
arg(1,K,T),
fetch_times(Vs, TVs).
sort_times([], _, []).
sort_times([T-V|TVs], Graph0, SortedVars) :-
fetch_same_time(TVs, T, Vars, NTVs),
fetch_parents([V|Vars],Edges),
add_edges(Graph0, Edges, Graph),
top_sort(Graph,SortedVars0,SortedVars),
sort_times(NTVs, Graph0, SortedVars0).
fetch_same_time([T-V|TVs], T, [V|Vs], TVs0) :- !,
fetch_same_time(TVs, T, Vs, TVs0).
fetch_same_time(TVs, _, [], TVs) :- !.
fetch_parents([],[]).
fetch_parents([V|Vars],EdgesF) :-
clpbn:get_atts(V,[dist(_,_,Parents)]),
exp_edges(Parents,V,EdgesF,Edges0),
fetch_parents(Vars,Edges0).
exp_edges([],_,Edges,Edges).
exp_edges([P|Parents],V,[V-P|Edges],Edges0) :-
exp_edges(Parents,V,Edges,Edges0).
extract_vars([],[]).
extract_vars([_-V|KVars],[V|Vars]) :-
extract_vars(KVars,Vars).
init_viterbi(V) :-
put_atts(V,[prob(0)]).
viterbi_alg([]).
viterbi_alg([V|Vs]) :-
% get the current status
get_atts(V,[prob(P0)]), !,
% clpbn:get_atts(V,[key(K)]),format('doing(~w)~n',[K]),
clpbn:get_atts(V,[dist(_,trans(Probs),States)]),
% adjust to consider emission probabilities
adjust_for_emission(V, P0, Pf),
propagate(Probs,States,Pf,V),
viterbi_alg(Vs).
viterbi_alg([_|Vs]) :-
viterbi_alg(Vs).
adjust_for_emission(V, P0, Pf) :-
get_atts(V,[emission(P)]), !,
mprob(P0,P,Pf),
put_atts(V,[prob(Pf)]).
adjust_for_emission(_, P, P).
propagate([],[],_,_).
propagate([-inf|Probs],[_|States],Pf,V) :- !,
propagate(Probs,States,Pf,V).
propagate([Prob|Probs],[State|States],Pf,V) :-
get_atts(State,[prob(P0)]), !,
mprob(Pf,Prob,P),
(P > P0 ->
put_atts(State,[prob(P),backp(V)])
;
true
),
% clpbn:get_atts(State,[key(K)]),format(' ~w: ~w -> ~w~n',[K,P0,P]),
propagate(Probs,States,Pf,V).
propagate([Prob|Probs],[State|States],Pf,V) :-
mprob(Pf,Prob,P),
put_atts(State,[prob(P),backp(V)]),
% clpbn:get_atts(State,[key(K)]),format(' ~w: ~w!!~n',[K,P]),
propagate(Probs,States,Pf,V).
backtrace(Start,Var,Trace,Trace) :- Start == Var, !.
backtrace(Start,Var,Trace0,Trace) :-
get_atts(Var,[backp(V)]),
clpbn:get_atts(Var, [key(K)]),
backtrace(Start,V,[K|Trace0],Trace).
mprob(*,_,-inf) :- !.
mprob(_,*,-inf) :- !.
mprob(P1,P2,P) :- P is P1+P2.