RandGen

Description

This operation randomly generates a set of successful paths in the input FST. The operation relies on an ArcSelector object for randomly selecting an outgoing transition at a given state in the input FST. The default arc selector, UniformArcSelector, randomly selects a transition using the uniform distribution. LogProbArcSelector randomly selects a transition w.r.t. the weights treated as negative log probabilities after normalizing for the total weight leaving the state. In all cases, finality is treated as a transition to a super-final state.

Usage

template <class Arc>
void RandGen(const Fst<Arc> &ifst, MutableFst<Arc> *ofst);

template <class Arc, class ArcSelector>
void RandGen(const Fst<Arc> &ifst, MutableFst<Arc> *ofst, const RandGenOptions<ArcSelector> &opts);

fstrandgen [--max_length=$l] [--npath=$n] [--seed=$s] [--select=$sel] in.fst out.fst 

Example

A:

Relabel(A, &B) using UniformArcSelector:

RandGen(A, &B);
RandGen(A, &B, RandGenOptions<UniformArcSelector<Arc> >(UniformArcSelector<Arc>()));

fstrandgen a.fst b.fst

Relabel(A, &B) using LogProbArcSelector:

RandGen(A, &B, RandGenOptions<LogProbArcSelector<Arc> >(LogProbArcSelector<Arc>()));

fstrandgen --select=log_prob a.fst b.fst

Complexity:

RandGen

• Time: O(N * L * c_T)
• Space: O(N * L + c_S)

-- CyrilAllauzen - 27 Mar 2009