diff options
author | Chris Dyer <redpony@gmail.com> | 2009-12-14 20:35:11 -0500 |
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committer | Chris Dyer <redpony@gmail.com> | 2009-12-14 20:35:11 -0500 |
commit | 851e389dffdd6996ea32d70defb8906de80b9edc (patch) | |
tree | 8c68ee77205badc056b8ab5b332e67e3e98017df /decoder/exp_semiring.h | |
parent | dc6930c00b4b276883280cff1ed6dcd9ddef03c7 (diff) |
few small fixes of alignment tools, add new orthographic similarity feature for word aligner, final naming of directories, libraries in cdec
Diffstat (limited to 'decoder/exp_semiring.h')
-rw-r--r-- | decoder/exp_semiring.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/decoder/exp_semiring.h b/decoder/exp_semiring.h new file mode 100644 index 00000000..f91beee4 --- /dev/null +++ b/decoder/exp_semiring.h @@ -0,0 +1,71 @@ +#ifndef _EXP_SEMIRING_H_ +#define _EXP_SEMIRING_H_ + +#include <iostream> + +// this file implements the first-order expectation semiring described +// in Li & Eisner (EMNLP 2009) + +// requirements: +// RType * RType ==> RType +// PType * PType ==> PType +// RType * PType ==> RType +// good examples: +// PType scalar, RType vector +// BAD examples: +// PType vector, RType scalar +template <typename PType, typename RType> +struct PRPair { + PRPair() : p(), r() {} + // Inside algorithm requires that T(0) and T(1) + // return the 0 and 1 values of the semiring + explicit PRPair(double x) : p(x), r() {} + PRPair(const PType& p, const RType& r) : p(p), r(r) {} + PRPair& operator+=(const PRPair& o) { + p += o.p; + r += o.r; + return *this; + } + PRPair& operator*=(const PRPair& o) { + r = (o.r * p) + (o.p * r); + p *= o.p; + return *this; + } + PType p; + RType r; +}; + +template <typename P, typename R> +std::ostream& operator<<(std::ostream& o, const PRPair<P,R>& x) { + return o << '<' << x.p << ", " << x.r << '>'; +} + +template <typename P, typename R> +const PRPair<P,R> operator+(const PRPair<P,R>& a, const PRPair<P,R>& b) { + PRPair<P,R> result = a; + result += b; + return result; +} + +template <typename P, typename R> +const PRPair<P,R> operator*(const PRPair<P,R>& a, const PRPair<P,R>& b) { + PRPair<P,R> result = a; + result *= b; + return result; +} + +template <typename P, typename PWeightFunction, typename R, typename RWeightFunction> +struct PRWeightFunction { + explicit PRWeightFunction(const PWeightFunction& pwf = PWeightFunction(), + const RWeightFunction& rwf = RWeightFunction()) : + pweight(pwf), rweight(rwf) {} + PRPair<P,R> operator()(const Hypergraph::Edge& e) const { + const P p = pweight(e); + const R r = rweight(e); + return PRPair<P,R>(p, r * p); + } + const PWeightFunction pweight; + const RWeightFunction rweight; +}; + +#endif |