```// Copyright (C) 2013  Davis E. King (davis@dlib.net)
#undef DLIB_AVERAGE_PREcISION_ABSTRACT_Hh_
#ifdef DLIB_AVERAGE_PREcISION_ABSTRACT_Hh_

#include <vector>

namespace dlib
{

// ----------------------------------------------------------------------------------------

template <
typename alloc
>
double average_precision (
const std::vector<bool,alloc>& items,
unsigned long missing_relevant_items = 0
);
/*!
ensures
- Interprets items as a list of relevant and non-relevant items in a response
from an information retrieval system.  In particular, items with a true value
are relevant and false items are non-relevant.  This function then returns
the average precision of the ranking of the given items.  For, example, the
ranking [true, true, true, true, false] would have an average precision of 1.
On the other hand, the ranking of [true false false true] would have an
average precision of 0.75 (because the first true has a precision of 1 and
the second true has a precision of 0.5, giving an average of 0.75).
- As a special case, if item contains no true elements then the average
precision is considered to be 1.
- Note that we use the interpolated precision.  That is, the interpolated
precision at a recall value r is set to the maximum precision obtained at any
higher recall value.  Or in other words, we interpolate the precision/recall
curve so that precision is monotonically decreasing.  Therefore, the average
precision value returned by this function is the area under this interpolated
precision/recall curve.
- This function will add in missing_relevant_items number of items with a
precision of zero into the average value returned.  For example, the average
precision of the ranking [true, true] if there are 2 missing relevant items
is 0.5.
!*/

// ----------------------------------------------------------------------------------------

template <
typename T,
typename alloc
>
double average_precision (
const std::vector<std::pair<T,bool>,alloc>& items,
unsigned long missing_relevant_items = 0
);
/*!
ensures
- this function is equivalent to copying the bool values from items into a
std::vector<bool> and then calling the above average_precision() routine on
it and returning the result.
!*/

// ----------------------------------------------------------------------------------------

}

#endif // DLIB_AVERAGE_PREcISION_ABSTRACT_Hh_

```