.. _program_listing_file_src_layers_lsh.h:

Program Listing for File lsh.h
==============================

|exhale_lsh| :ref:`Return to documentation for file <file_src_layers_lsh.h>` (``src/layers/lsh.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #pragma once
   
   #include "graph/expression_operators.h"
   #include "graph/node_initializers.h"
   
   #include <vector>
   
   namespace marian {
   namespace lsh {
     // encodes an input as a bit vector, with optional rotation
     Expr encode(Expr input, Expr rotator = nullptr);
   
     // compute the rotation matrix (maps weights->shape()[-1] to nbits floats)
     Expr rotator(Expr weights, int inDim, int nbits);
   
     // perform the LSH search on fully encoded input and weights, return k results (indices) per input row
     // @TODO: add a top-k like operator that also returns the bitwise computed distances
     Expr searchEncoded(Expr encodedQuery, Expr encodedWeights, int k, int firstNRows = 0, bool noSort = false);
   
     // same as above, but performs encoding on the fly
     Expr search(Expr query, Expr weights, int k, int nbits, int firstNRows = 0, bool abortIfDynamic = false);
     
     // struct for parameter conversion used in marian-conv
     struct ParamConvInfo {
       std::string name;
       std::string codesName;
       std::string rotationName;
       int nBits;
       bool transpose;
   
       ParamConvInfo(const std::string& name, const std::string& codesName, const std::string& rotationName, int nBits, bool transpose = false) 
        : name(name), codesName(codesName), rotationName(rotationName), nBits(nBits), transpose(transpose) {}
     };
   
     // These are helper functions for encoding the LSH into the binary Marian model, used by marian-conv
     void addDummyParameters(Ptr<ExpressionGraph> graph, ParamConvInfo paramInfo);
     void overwriteDummyParameters(Ptr<ExpressionGraph> graph, ParamConvInfo paramInfo);
   
     Ptr<inits::NodeInitializer> randomRotation();
   }
   
   }