/// <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]);
}
}
}
/// <summary>
/// Make an in-place Kleene closure of the FST.
/// </summary>
public static void fst_star(IGenericFst fst)
{
int s = fst.GetStart();
fst.SetAccept(s);
for (int i = 0; i < fst.nStates(); i++)
{
double c = fst.GetAcceptCost(i);
if (c < 1e37)
{
fst.AddTransition(i, s, 0, (float)c, 0);
}
}
}
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);
}
public override float GetAcceptCost(int node)
{
int i1 = node / l2.nStates();
int i2 = node % l2.nStates();
float cost1;
if (override_finish >= 0)
{
cost1 = i1 == override_finish ? 0f : 1e38f;
}
else
{
cost1 = l1.GetAcceptCost(i1);
}
return(cost1 + l2.GetAcceptCost(i2));
}
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));
}
}
}