/// <summary>
/// Randomly sample an FST, assuming any input.
/// </summary>
/// <param name="result">The array of output symbols, excluding epsilons.</param>
/// <param name="fst">The FST.</param>
/// <param name="max">The maximum length of the result.</param>
/// <returns>total cost</returns>
public static double fst_sample(Intarray result, IGenericFst fst, int max = 1000)
{
double total_cost = 0;
int current = fst.GetStart();
for (int counter = 0; counter < max; counter++)
{
Intarray inputs = new Intarray();
Intarray outputs = new Intarray();
Intarray targets = new Intarray();
Floatarray costs = new Floatarray();
fst.Arcs(inputs, targets, outputs, costs, current);
// now we need to deal with the costs uniformly, so:
costs.Push(fst.GetAcceptCost(current));
int choice = sample_by_costs(costs);
if (choice == costs.Length() - 1)
{
break;
}
result.Push(outputs[choice]);
total_cost += costs[choice];
current = targets[choice];
}
return(total_cost + fst.GetAcceptCost(current));
}
/// <summary>
/// Copy one FST to another.
/// </summary>
/// <param name="dst">The destination. Will be cleared before copying.</param>
/// <param name="src">The FST to copy.</param>
public static void fst_copy(IGenericFst dst, IGenericFst src)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i < n; i++)
{
dst.NewState();
}
dst.SetStart(src.GetStart());
for (int i = 0; i < n; i++)
{
dst.SetAccept(i, src.GetAcceptCost(i));
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
int inlen = inputs.Length();
if (inlen != targets.Length())
{
throw new Exception("ASSERT: inputs.length() == targets.length()");
}
if (inlen != outputs.Length())
{
throw new Exception("ASSERT: inputs.length() == outputs.length()");
}
if (inlen != costs.Length())
{
throw new Exception("ASSERT: inputs.length() == costs.length()");
}
for (int j = 0; j < inputs.Length(); j++)
{
dst.AddTransition(i, targets.At1d(j), outputs.At1d(j), costs.At1d(j), inputs.At1d(j));
}
}
}
/// <summary>
/// Copy one FST to another, preserving only lowest-cost arcs.
/// This is useful for visualization.
/// </summary>
/// <param name="dst">The destination. Will be cleared before copying.</param>
/// <param name="src">The FST to copy.</param>
public static void fst_copy_best_arcs_only(IGenericFst dst, IGenericFst src)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i < n; i++)
{
dst.NewState();
}
dst.SetStart(src.GetStart());
for (int i = 0; i < n; i++)
{
dst.SetAccept(i, src.GetAcceptCost(i));
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
int inlen = inputs.Length();
if (inlen != targets.Length())
{
throw new Exception("ASSERT: inputs.length() == targets.length()");
}
if (inlen != outputs.Length())
{
throw new Exception("ASSERT: inputs.length() == outputs.length()");
}
if (inlen != costs.Length())
{
throw new Exception("ASSERT: inputs.length() == costs.length()");
}
Dictionary <int, int> hash = new Dictionary <int, int>();
for (int j = 0; j < n; j++)
{
int t = targets[j];
int best_so_far = -1;
if (hash.ContainsKey(t))
{
best_so_far = hash[t];
}
if (best_so_far == -1 || costs[j] < costs[best_so_far])
{
hash[t] = j;
}
}
Intarray keys = new Intarray();
//hash.keys(keys);
keys.Clear();
foreach (int key in hash.Keys)
{
keys.Push(key);
}
for (int k = 0; k < keys.Length(); k++)
{
int j = hash[keys[k]];
dst.AddTransition(i, targets[j], outputs[j], costs[j], inputs[j]);
}
}
}
public bool Step()
{
int node = heap.Pop();
if (node == n)
{
return(true); // accept has popped up
}
// get outbound arcs
Intarray inputs = new Intarray();
Intarray targets = new Intarray();
Intarray outputs = new Intarray();
Floatarray costs = new Floatarray();
fst.Arcs(inputs, targets, outputs, costs, node);
for (int i = 0; i < targets.Length(); i++)
{
int t = targets[i];
if (came_from[t] == -1 || g[node] + costs[i] < g[t])
{
// relax the edge
came_from[t] = node;
g[t] = g[node] + costs[i];
heap.Push(t, g[t] + Convert.ToSingle(Heuristic(t)));
}
}
if (accepted_from == -1 ||
g[node] + fst.GetAcceptCost(node) < g_accept)
{
// relax the accept edge
accepted_from = node;
g_accept = g[node] + fst.GetAcceptCost(node);
heap.Push(n, g_accept);
}
return(false);
}
protected static void write_node(BinaryWriter writer, IGenericFst fst, int index)
{
Intarray inputs = new Intarray();
Intarray targets = new Intarray();
Intarray outputs = new Intarray();
Floatarray costs = new Floatarray();
fst.Arcs(inputs, targets, outputs, costs, index);
int narcs = targets.Length();
write_float(writer, fst.GetAcceptCost(index));
write_int64_LE(writer, narcs);
for (int i = 0; i < narcs; i++)
{
write_int32_LE(writer, inputs[i]);
write_int32_LE(writer, outputs[i]);
write_float(writer, costs[i]);
write_int32_LE(writer, targets[i]);
}
}
/// <summary>
/// Reverse the FST's arcs, adding a new start vertex (former accept).
/// </summary>
public static void fst_copy_reverse(IGenericFst dst, IGenericFst src, bool no_accept = false)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i <= n; i++)
{
dst.NewState();
}
if (!no_accept)
{
dst.SetAccept(src.GetStart());
}
dst.SetStart(n);
for (int i = 0; i < n; i++)
{
dst.AddTransition(n, i, 0, src.GetAcceptCost(i), 0);
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
if (inputs.Length() != targets.Length())
{
throw new Exception("ASSERT: inputs.length() == targets.length()");
}
if (inputs.Length() != outputs.Length())
{
throw new Exception("ASSERT: inputs.length() == outputs.length()");
}
if (inputs.Length() != costs.Length())
{
throw new Exception("ASSERT: inputs.length() == costs.length()");
}
for (int j = 0; j < inputs.Length(); j++)
{
dst.AddTransition(targets.At1d(j), i, outputs.At1d(j), costs.At1d(j), inputs.At1d(j));
}
}
}
public override void Arcs(Intarray ids, Intarray targets, Intarray outputs, Floatarray costs, int node)
{
int n1 = node / l2.nStates();
int n2 = node % l2.nStates();
Intarray ids1 = new Intarray();
Intarray ids2 = new Intarray();
Intarray t1 = new Intarray();
Intarray t2 = new Intarray();
Intarray o1 = new Intarray();
Intarray o2 = new Intarray();
Floatarray c1 = new Floatarray();
Floatarray c2 = new Floatarray();
l1.Arcs(ids1, t1, o1, c1, n1);
l2.Arcs(ids2, t2, o2, c2, n2);
// sort & permute
Intarray p1 = new Intarray();
Intarray p2 = new Intarray();
NarrayUtil.Quicksort(p1, o1);
NarrayUtil.Permute(ids1, p1);
NarrayUtil.Permute(t1, p1);
NarrayUtil.Permute(o1, p1);
NarrayUtil.Permute(c1, p1);
NarrayUtil.Quicksort(p2, ids2);
NarrayUtil.Permute(ids2, p2);
NarrayUtil.Permute(t2, p2);
NarrayUtil.Permute(o2, p2);
NarrayUtil.Permute(c2, p2);
int k1, k2;
// l1 epsilon moves
for (k1 = 0; k1 < o1.Length() && o1.At1d(k1) == 0; k1++)
{
ids.Push(ids1.At1d(k1));
targets.Push(Combine(t1.At1d(k1), n2));
outputs.Push(0);
costs.Push(c1.At1d(k1));
}
// l2 epsilon moves
for (k2 = 0; k2 < o2.Length() && ids2.At1d(k2) == 0; k2++)
{
ids.Push(0);
targets.Push(Combine(n1, t2.At1d(k2)));
outputs.Push(o2.At1d(k2));
costs.Push(c2.At1d(k2));
}
// non-epsilon moves
while (k1 < o1.Length() && k2 < ids2.Length())
{
while (k1 < o1.Length() && o1.At1d(k1) < ids2.At1d(k2))
{
k1++;
}
if (k1 >= o1.Length())
{
break;
}
while (k2 < ids2.Length() && o1.At1d(k1) > ids2.At1d(k2))
{
k2++;
}
while (k1 < o1.Length() && k2 < ids2.Length() && o1.At1d(k1) == ids2.At1d(k2))
{
for (int j = k2; j < ids2.Length() && o1.At1d(k1) == ids2.At1d(j); j++)
{
ids.Push(ids1.At1d(k1));
targets.Push(Combine(t1.At1d(k1), t2.At1d(j)));
outputs.Push(o2.At1d(j));
costs.Push(c1.At1d(k1) + c2.At1d(j));
}
k1++;
}
}
}