Re: [Boost-users] ranking of ublas vector

Subject: Re: [Boost-users] ranking of ublas vector
From: Kraus Philipp (philipp.kraus_at_[hidden])
Date: 2010-03-13 16:53:05

Am 13.03.2010 um 22:18 schrieb Steven Watanabe:

> AMDG
>
> Kraus Philipp wrote:
>> I have a very large non sparse ublas vector (most long double  
>> content).
>> I would like to sort this vector without change the vector content,  
>> but
>> I know the rank of the elements like
>>
>> the smalest element in the vector is the 312 element in the original
>> vector (for example).
>>
>> Is there a boost implementation for create ranking of elements?
>
> There isn't, but it's fairly straightforward to do.
>
> ublas::vector<long double> vec;
>
> using namespace boost::lambda;
> std::vector<std::size_t>  
> temp(boost::counting_iterator<std::size_t>(0),  
> boost::counting_iterator<std::size_t>(vec.size()));
> std::sort(temp.begin(), temp.end(), var(vec)[_1] < var(vec)[_2]);
> std::vector<std::size_t> ranking(temp.size());
> std::copy(boost::counting_iterator<std::size_t>(0),  
> boost::counting_iterator<std::size_t>(vec.size()),
>   boost::make_permutation_iterator(ranking.begin(), temp.begin()));

I have a problem with the boost libs (1.42). Your code compiles  
without errors, but
in the "operator_lambda_func_base.hpp" at line 135 the compilere shows  
the error
4 times:
conversion from 'double' to non-scalar type  
'boost::lambda::detail::unspecified' requested

I have set this includes:
#include <boost/iterator/counting_iterator.hpp>
#include <boost/iterator/permutation_iterator.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/numeric/ublas/vector.hpp>

Can you please help to solve this problem?

Thank

Phil