# cython: profile=True, experimental_cpp_class_def=True, cdivision=True, infer_types=True cimport cython from libc.math cimport exp, log from libc.string cimport memcpy, memset import math from cymem.cymem cimport Pool from preshed.maps cimport PreshMap cdef class Beam: def __init__(self, class_t nr_class, class_t width, weight_t min_density=0.0): assert nr_class != 0 assert width != 0 self.nr_class = nr_class self.width = width self.min_density = min_density self.size = 1 self.t = 0 self.mem = Pool() self.del_func = NULL self._parents = <_State*>self.mem.alloc(self.width, sizeof(_State)) self._states = <_State*>self.mem.alloc(self.width, sizeof(_State)) cdef int i self.histories = [[] for i in range(self.width)] self._parent_histories = [[] for i in range(self.width)] self.scores = self.mem.alloc(self.width, sizeof(weight_t*)) self.is_valid = self.mem.alloc(self.width, sizeof(weight_t*)) self.costs = self.mem.alloc(self.width, sizeof(weight_t*)) for i in range(self.width): self.scores[i] = self.mem.alloc(self.nr_class, sizeof(weight_t)) self.is_valid[i] = self.mem.alloc(self.nr_class, sizeof(int)) self.costs[i] = self.mem.alloc(self.nr_class, sizeof(weight_t)) def __len__(self): return self.size property score: def __get__(self): return self._states[0].score property min_score: def __get__(self): return self._states[self.size-1].score property loss: def __get__(self): return self._states[0].loss property probs: def __get__(self): return _softmax([self._states[i].score for i in range(self.size)]) property scores: def __get__(self): return [self._states[i].score for i in range(self.size)] property histories: def __get__(self): return self.histories cdef int set_row(self, int i, const weight_t* scores, const int* is_valid, const weight_t* costs) except -1: cdef int j for j in range(self.nr_class): self.scores[i][j] = scores[j] self.is_valid[i][j] = is_valid[j] self.costs[i][j] = costs[j] cdef int set_table(self, weight_t** scores, int** is_valid, weight_t** costs) except -1: cdef int i, j for i in range(self.width): memcpy(self.scores[i], scores[i], sizeof(weight_t) * self.nr_class) memcpy(self.is_valid[i], is_valid[i], sizeof(bint) * self.nr_class) memcpy(self.costs[i], costs[i], sizeof(int) * self.nr_class) cdef int initialize(self, init_func_t init_func, del_func_t del_func, int n, void* extra_args) except -1: for i in range(self.width): self._states[i].content = init_func(self.mem, n, extra_args) self._parents[i].content = init_func(self.mem, n, extra_args) self.del_func = del_func def __dealloc__(self): if self.del_func == NULL: return for i in range(self.width): self.del_func(self.mem, self._states[i].content, NULL) self.del_func(self.mem, self._parents[i].content, NULL) @cython.cdivision(True) cdef int advance(self, trans_func_t transition_func, hash_func_t hash_func, void* extra_args) except -1: cdef weight_t** scores = self.scores cdef int** is_valid = self.is_valid cdef weight_t** costs = self.costs cdef Queue* q = new Queue() self._fill(q, scores, is_valid) # For a beam of width k, we only ever need 2k state objects. How? # Each transition takes a parent and a class and produces a new state. # So, we don't need the whole history --- just the parent. So at # each step, we take a parent, and apply one or more extensions to # it. self._parents, self._states = self._states, self._parents self._parent_histories, self.histories = self.histories, self._parent_histories cdef weight_t score cdef int p_i cdef int i = 0 cdef class_t clas cdef _State* parent cdef _State* state cdef hash_t key cdef PreshMap seen_states = PreshMap(self.width) cdef uint64_t is_seen cdef uint64_t one = 1 while i < self.width and not q.empty(): data = q.top() p_i = data.second / self.nr_class clas = data.second % self.nr_class score = data.first q.pop() parent = &self._parents[p_i] # Indicates terminal state reached; i.e. state is done if parent.is_done: # Now parent will not be changed, so we don't have to copy. # Once finished, should also be unbranching. self._states[i], parent[0] = parent[0], self._states[i] parent.i = self._states[i].i parent.t = self._states[i].t parent.is_done = self._states[i].t self._states[i].score = score self.histories[i] = list(self._parent_histories[p_i]) i += 1 else: state = &self._states[i] # The supplied transition function should adjust the destination # state to be the result of applying the class to the source state transition_func(state.content, parent.content, clas, extra_args) key = hash_func(state.content, extra_args) if hash_func is not NULL else 0 is_seen = seen_states.get(key) if key == 0 or key == 1 or not is_seen: if key != 0 and key != 1: seen_states.set(key, one) state.score = score state.loss = parent.loss + costs[p_i][clas] self.histories[i] = list(self._parent_histories[p_i]) self.histories[i].append(clas) i += 1 del q self.size = i assert self.size >= 1 for i in range(self.width): memset(self.scores[i], 0, sizeof(weight_t) * self.nr_class) memset(self.costs[i], 0, sizeof(weight_t) * self.nr_class) memset(self.is_valid[i], 0, sizeof(int) * self.nr_class) self.t += 1 cdef int check_done(self, finish_func_t finish_func, void* extra_args) except -1: cdef int i for i in range(self.size): if not self._states[i].is_done: self._states[i].is_done = finish_func(self._states[i].content, extra_args) for i in range(self.size): if not self._states[i].is_done: self.is_done = False break else: self.is_done = True @cython.cdivision(True) cdef int _fill(self, Queue* q, weight_t** scores, int** is_valid) except -1: """Populate the queue from a k * n matrix of scores, where k is the beam-width, and n is the number of classes. """ cdef Entry entry cdef weight_t score cdef _State* s cdef int i, j, move_id assert self.size >= 1 cdef vector[Entry] entries for i in range(self.size): s = &self._states[i] move_id = i * self.nr_class if s.is_done: # Update score by path average, following TACL '13 paper. if self.histories[i]: entry.first = s.score + (s.score / self.t) else: entry.first = s.score entry.second = move_id entries.push_back(entry) else: for j in range(self.nr_class): if is_valid[i][j]: entry.first = s.score + scores[i][j] entry.second = move_id + j entries.push_back(entry) cdef double max_, Z, cutoff if self.min_density == 0.0: for i in range(entries.size()): q.push(entries[i]) elif not entries.empty(): max_ = entries[0].first Z = 0. cutoff = 0. # Softmax into probabilities, so we can prune for i in range(entries.size()): if entries[i].first > max_: max_ = entries[i].first for i in range(entries.size()): Z += exp(entries[i].first-max_) cutoff = (1. / Z) * self.min_density for i in range(entries.size()): prob = exp(entries[i].first-max_) / Z if prob >= cutoff: q.push(entries[i]) cdef class MaxViolation: def __init__(self): self.p_score = 0.0 self.g_score = 0.0 self.Z = 0.0 self.gZ = 0.0 self.delta = -1 self.cost = 0 self.p_hist = [] self.g_hist = [] self.p_probs = [] self.g_probs = [] cpdef int check(self, Beam pred, Beam gold) except -1: cdef _State* p = &pred._states[0] cdef _State* g = &gold._states[0] cdef weight_t d = p.score - g.score if p.loss >= 1 and (self.cost == 0 or d > self.delta): self.cost = p.loss self.delta = d self.p_hist = list(pred.histories[0]) self.g_hist = list(gold.histories[0]) self.p_score = p.score self.g_score = g.score self.Z = 1e-10 self.gZ = 1e-10 for i in range(pred.size): if pred._states[i].loss > 0: self.Z += exp(pred._states[i].score) for i in range(gold.size): if gold._states[i].loss == 0: prob = exp(gold._states[i].score) self.Z += prob self.gZ += prob cpdef int check_crf(self, Beam pred, Beam gold) except -1: d = pred.score - gold.score seen_golds = set([tuple(gold.histories[i]) for i in range(gold.size)]) if pred.loss > 0 and (self.cost == 0 or d > self.delta): p_hist = [] p_scores = [] g_hist = [] g_scores = [] for i in range(pred.size): if pred._states[i].loss > 0: p_scores.append(pred._states[i].score) p_hist.append(list(pred.histories[i])) # This can happen from non-monotonic actions # If we find a better gold analysis this way, be sure to keep it. elif pred._states[i].loss <= 0 \ and tuple(pred.histories[i]) not in seen_golds: g_scores.append(pred._states[i].score) g_hist.append(list(pred.histories[i])) for i in range(gold.size): if gold._states[i].loss == 0: g_scores.append(gold._states[i].score) g_hist.append(list(gold.histories[i])) all_probs = _softmax(p_scores + g_scores) p_probs = all_probs[:len(p_scores)] g_probs_all = all_probs[len(p_scores):] g_probs = _softmax(g_scores) self.cost = pred.loss self.delta = d self.p_hist = p_hist self.g_hist = g_hist # TODO: These variables are misnamed! These are the gradients of the loss. self.p_probs = p_probs # Intuition here: # The gradient of the loss is: # P(model) - P(truth) # Normally, P(truth) is 1 for the gold # But, if we want to do the "partial credit" scheme, we want # to create a distribution over the gold, proportional to the scores # awarded. self.g_probs = [x-y for x, y in zip(g_probs_all, g_probs)] def _softmax(nums): if not nums: return [] max_ = max(nums) nums = [(exp(n-max_) if n is not None else None) for n in nums] Z = sum(n for n in nums if n is not None) return [(n/Z if n is not None else None) for n in nums]