thrust

#include <thrust/functional.h>
Public Types  
typedef T1  first_argument_type 
The type of the function object's first argument.  
typedef T2  second_argument_type 
The type of the function object's second argument.  
typedef T2  result_type 
The type of the function object's result;.  
Public Member Functions  
__host__ __device__ const T2 &  operator() (const T1 &, const T2 &rhs) const 
project2nd
is a function object that takes two arguments and returns its second argument; the first argument is unused. It is essentially a generalization of identity to the case of a Binary Function.