libigl/include/igl/slice.cpp

// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2013 Alec Jacobson <[email protected]>
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.
#include "slice.h"
#include "colon.h"

#include <cassert>
#include <vector>

template <
    typename TX,
    typename TY,
    typename DerivedR,
    typename DerivedC>
IGL_INLINE void igl::slice(
    const Eigen::SparseMatrix<TX> &X,
    const Eigen::DenseBase<DerivedR> &R,
    const Eigen::DenseBase<DerivedC> &C,
    Eigen::SparseMatrix<TY> &Y)
{
  int xm = X.rows();
  int xn = X.cols();
  int ym = R.size();
  int yn = C.size();

  // special case when R or C is empty
  if (ym == 0 || yn == 0)
  {
    Y.resize(ym, yn);
    return;
  }

  assert(R.minCoeff() >= 0);
  assert(R.maxCoeff() < xm);
  assert(C.minCoeff() >= 0);
  assert(C.maxCoeff() < xn);

  // Build reindexing maps for columns and rows
  std::vector<std::vector<typename DerivedR::Scalar>> RI;
  RI.resize(xm);
  for (int i = 0; i < ym; i++)
  {
    RI[R(i)].push_back(i);
  }
  std::vector<std::vector<typename DerivedC::Scalar>> CI;
  CI.resize(xn);
  for (int i = 0; i < yn; i++)
  {
    CI[C(i)].push_back(i);
  }

  // Take a guess at the number of nonzeros (this assumes uniform distribution
  // not banded or heavily diagonal)
  std::vector<Eigen::Triplet<TY>> entries;
  entries.reserve((X.nonZeros()/(X.rows()*X.cols())) * (ym*yn));

  // Iterate over outside
  for (int k = 0; k < X.outerSize(); ++k)
  {
    // Iterate over inside
    for (typename Eigen::SparseMatrix<TX>::InnerIterator it(X, k); it; ++it)
    {
      for (auto rit = RI[it.row()].begin(); rit != RI[it.row()].end(); rit++)
      {
        for (auto cit = CI[it.col()].begin(); cit != CI[it.col()].end(); cit++)
        {
          entries.emplace_back(*rit, *cit, it.value());
        }
      }
    }
  }
  Y.resize(ym, yn);
  Y.setFromTriplets(entries.begin(), entries.end());
}

template <typename MatX, typename DerivedR, typename MatY>
IGL_INLINE void igl::slice(
    const MatX &X,
    const Eigen::DenseBase<DerivedR> &R,
    const int dim,
    MatY &Y)
{
  Eigen::Matrix<typename DerivedR::Scalar, Eigen::Dynamic, 1> C;
  switch (dim)
  {
  case 1:
    // boring base case
    if (X.cols() == 0)
    {
      Y.resize(R.size(), 0);
      return;
    }
    igl::colon(0, X.cols() - 1, C);
    return slice(X, R, C, Y);
  case 2:
    // boring base case
    if (X.rows() == 0)
    {
      Y.resize(0, R.size());
      return;
    }
    igl::colon(0, X.rows() - 1, C);
    return slice(X, C, R, Y);
  default:
    assert(false && "Unsupported dimension");
    return;
  }
}

template <
    typename DerivedX,
    typename DerivedR,
    typename DerivedC,
    typename DerivedY>
IGL_INLINE void igl::slice(
    const Eigen::DenseBase<DerivedX> &X,
    const Eigen::DenseBase<DerivedR> &R,
    const Eigen::DenseBase<DerivedC> &C,
    Eigen::PlainObjectBase<DerivedY> &Y)
{
#ifndef NDEBUG
  int xm = X.rows();
  int xn = X.cols();
#endif
  int ym = R.size();
  int yn = C.size();

  // special case when R or C is empty
  if (ym == 0 || yn == 0)
  {
    Y.resize(ym, yn);
    return;
  }

  assert(R.minCoeff() >= 0);
  assert(R.maxCoeff() < xm);
  assert(C.minCoeff() >= 0);
  assert(C.maxCoeff() < xn);

  // Resize output
  Y.resize(ym, yn);
  // loop over output rows, then columns
  for (int i = 0; i < ym; i++)
  {
    for (int j = 0; j < yn; j++)
    {
      Y(i, j) = X(R(i), C(j));
    }
  }
}

template <typename DerivedX, typename DerivedY, typename DerivedR>
IGL_INLINE void igl::slice(
    const Eigen::DenseBase<DerivedX> &X,
    const Eigen::DenseBase<DerivedR> &R,
    Eigen::PlainObjectBase<DerivedY> &Y)
{
  // phony column indices
  Eigen::Matrix<typename DerivedR::Scalar, Eigen::Dynamic, 1> C;
  C.resize(1);
  C(0) = 0;
  return igl::slice(X, R, C, Y);
}

template <typename DerivedX, typename DerivedR>
IGL_INLINE DerivedX igl::slice(
    const Eigen::DenseBase<DerivedX> &X,
    const Eigen::DenseBase<DerivedR> &R)
{
  // This is not safe. See PlainMatrix
  DerivedX Y;
  igl::slice(X, R, Y);
  return Y;
}

template <typename DerivedX, typename DerivedR>
IGL_INLINE DerivedX igl::slice(
    const Eigen::DenseBase<DerivedX> &X,
    const Eigen::DenseBase<DerivedR> &R,
    const int dim)
{
  // This is not safe. See PlainMatrix
  DerivedX Y;
  igl::slice(X, R, dim, Y);
  return Y;
}

template< class T >
IGL_INLINE void igl::slice(
  const std::vector<T> & unordered,
  std::vector<size_t> const & index_map,
  std::vector<T> & ordered)
{
  // copy for the slice according to index_map, because unordered may also be
  // ordered
  std::vector<T> copy = unordered;
  ordered.resize(index_map.size());
  for(int i = 0; i<(int)index_map.size();i++)
  {
    ordered[i] = copy[index_map[i]];
  }
}


#ifdef IGL_STATIC_LIBRARY
// Explicit template instantiation
template void igl::slice<std::int64_t>(std::vector<std::int64_t, std::allocator<std::int64_t>> const&, std::vector<size_t, std::allocator<size_t>> const&, std::vector<std::int64_t, std::allocator<std::int64_t>>&);

template void igl::slice<Eigen::SparseMatrix<bool, 0, int>, Eigen::Matrix<int, -1, 1, 0, -1, 1>, Eigen::SparseMatrix<bool, 0, int>>(Eigen::SparseMatrix<bool, 0, int> const &, Eigen::DenseBase<Eigen::Matrix<int, -1, 1, 0, -1, 1>> const &, int, Eigen::SparseMatrix<bool, 0, int> &);
template void igl::slice<Eigen::SparseMatrix<double, 0, int>, Eigen::Array<int, -1, 1, 0, -1, 1>, Eigen::SparseMatrix<double, 0, int> >(Eigen::SparseMatrix<double, 0, int> const&, Eigen::DenseBase<Eigen::Array<int, -1, 1, 0, -1, 1> > const&, int, Eigen::SparseMatrix<double, 0, int>&);
template void igl::slice<Eigen::SparseMatrix<double, 0, int>, Eigen::Matrix<double, -1, 1, 0, -1, 1>, Eigen::SparseMatrix<double, 0, int>>(Eigen::SparseMatrix<double, 0, int> const &, Eigen::DenseBase<Eigen::Matrix<double, -1, 1, 0, -1, 1>> const &, int, Eigen::SparseMatrix<double, 0, int> &);
template void igl::slice<Eigen::SparseMatrix<double, 0, int>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::SparseMatrix<double, 0, int>>(Eigen::SparseMatrix<double, 0, int> const &, Eigen::DenseBase<Eigen::Matrix<int, -1, -1, 0, -1, -1>> const &, int, Eigen::SparseMatrix<double, 0, int> &);
template void igl::slice<Eigen::SparseMatrix<double, 0, int>, Eigen::Matrix<int, -1, 1, 0, -1, 1>, Eigen::SparseMatrix<double, 0, int>>(Eigen::SparseMatrix<double, 0, int> const &, Eigen::DenseBase<Eigen::Matrix<int, -1, 1, 0, -1, 1>> const &, int, Eigen::SparseMatrix<double, 0, int> &);
#ifdef WIN32
template void igl::slice<unsigned int>(class std::vector<unsigned int,class std::allocator<unsigned int> > const &,class std::vector<unsigned __int64,class std::allocator<unsigned __int64> > const &,class std::vector<unsigned int,class std::allocator<unsigned int> > &);
template void igl::slice<float>(class std::vector<float,class std::allocator<float> > const &,class std::vector<unsigned __int64,class std::allocator<unsigned __int64> > const &,class std::vector<float,class std::allocator<float> > &);
template void igl::slice<__int64>(class std::vector<__int64,class std::allocator<__int64> > const &,class std::vector<unsigned __int64,class std::allocator<unsigned __int64> > const &,class std::vector<__int64,class std::allocator<__int64> > &);
#endif
template void igl::slice<unsigned int>(std::vector<unsigned int, std::allocator<unsigned int> > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<unsigned int, std::allocator<unsigned int> >&);
template void igl::slice<float>(std::vector<float, std::allocator<float> > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<float, std::allocator<float> >&);
template void igl::slice<double>(std::vector<double, std::allocator<double> > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<double, std::allocator<double> >&);
template void igl::slice<int>(std::vector<int, std::allocator<int> > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<int, std::allocator<int> >&);
#include "SortableRow.h"
template void igl::slice<igl::SortableRow<Eigen::Matrix<int, -1, 1, 0, -1, 1> > >(std::vector<igl::SortableRow<Eigen::Matrix<int, -1, 1, 0, -1, 1> >, std::allocator<igl::SortableRow<Eigen::Matrix<int, -1, 1, 0, -1, 1> > > > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<igl::SortableRow<Eigen::Matrix<int, -1, 1, 0, -1, 1> >, std::allocator<igl::SortableRow<Eigen::Matrix<int, -1, 1, 0, -1, 1> > > >&);
template void igl::slice<igl::SortableRow<Eigen::Matrix<double, -1, 1, 0, -1, 1> > >(std::vector<igl::SortableRow<Eigen::Matrix<double, -1, 1, 0, -1, 1> >, std::allocator<igl::SortableRow<Eigen::Matrix<double, -1, 1, 0, -1, 1> > > > const&, std::vector<size_t, std::allocator<size_t> > const&, std::vector<igl::SortableRow<Eigen::Matrix<double, -1, 1, 0, -1, 1> >, std::allocator<igl::SortableRow<Eigen::Matrix<double, -1, 1, 0, -1, 1> > > >&);
#endif