Transition Matrix_to_Transition (Matrix me) {
try {
if (my nx != my ny)
Melder_throw ("Matrix should be square.");
autoTransition thee = Transition_create (my nx);
for (long i = 1; i <= my nx; i ++)
for (long j = 1; j <= my nx; j ++)
thy data [i] [j] = my z [i] [j];
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": not converted to Transition.");
}
}
Transition Distributions_to_Transition (Distributions underlying, Distributions surface, long environment,
Transition adjacency, int greedy)
{
if (underlying == NULL) return NULL;
Transition thee = NULL;
/*
* Preconditions: range check and matrix matching.
*/
if (environment < 1 || environment > underlying -> numberOfColumns)
error5 (L"Environment (", Melder_integer (environment), L") out of range (1-", Melder_integer (underlying -> numberOfColumns), L").")
if (surface && (underlying -> numberOfColumns != surface -> numberOfColumns || underlying -> numberOfRows != surface -> numberOfRows))
error1 (L"Sizes of underlying and surface distributions do not match.")
if (adjacency && adjacency -> numberOfStates != underlying -> numberOfColumns)
error5 (L"Number of states (", Melder_integer (adjacency -> numberOfStates), L") in adjacency matrix "
"does not match number of distributions (", Melder_integer (underlying -> numberOfColumns), L")")
/*
* Defaults.
*/
if (surface == NULL) surface = underlying;
/*
* Create the output object.
*/
thee = Transition_create (underlying -> numberOfColumns); cherror
/*
* Copy labels and set name.
*/
for (long i = 1; i <= thy numberOfStates; i ++) {
thy stateLabels [i] = Melder_wcsdup_e (underlying -> columnLabels [i]); cherror
}
Thing_setName (thee, underlying -> columnLabels [environment]); cherror
/*
* Compute the off-diagonal elements of the transition matrix in environment 'environment'.
*/
for (long i = 1; i <= thy numberOfStates; i ++) {
/*
* How many states are available for the learner to step to (excluding current state)?
*/
long numberOfAdjacentStates;
if (adjacency) {
numberOfAdjacentStates = 0;
for (long j = 1; j <= thy numberOfStates; j ++)
if (i != j && adjacency -> data [i] [j])
numberOfAdjacentStates ++;
} else {
numberOfAdjacentStates = thy numberOfStates - 1;
}
/*
* Try all possible steps to adjacent states.
*/
for (long j = 1; j <= thy numberOfStates; j ++) if (i != j) {
/*
* Local: grammar step only possible to adjacent grammar.
*/
if (adjacency && adjacency -> data [i] [j] == 0) continue;
/*
* Compute element (i, j): sum over all possible data.
*/
for (long m = 1; m <= underlying -> numberOfRows; m ++) {
/*
* Error-driven: grammar step only triggered by positive evidence.
* If the datum does not conflict with the current hypothesis (i), ignore it.
*/
if (underlying -> data [m] [i]) continue;
/*
* Greedy: grammar step only taken if new grammar accepts datum.
*/
if (greedy && underlying -> data [m] [j] == 0) continue;
/*
* The step is taken if this datum occurs and this grammar (j) is chosen.
*/
thy data [i] [j] += surface -> data [m] [environment] / numberOfAdjacentStates;
}
}
}
/*
* Compute the elements on the diagonal, so that the sum of each row is unity.
*/
for (long i = 1; i <= thy numberOfStates; i ++) {
double sum = 0.0;
for (long j = 1; j <= thy numberOfStates; j ++) if (j != i)
sum += thy data [i] [j];
thy data [i] [i] = sum > 1.0 ? 0.0 : 1.0 - sum; /* Guard against rounding errors. */
}
end:
iferror {
forget (thee);
return (structTransition *)Melder_errorp1 (L"Distributions to Transition: not performed.");
}
return thee;
}
