Calculate contour lines from a twodimensional data set. More...
#include <contour.h>
Public Types  
typedef boost::numeric::ublas::vector< double >  ubvector 
typedef boost::numeric::ublas::vector< int >  ubvector_int 
typedef boost::numeric::ublas::matrix< double >  ubmatrix 
Public Member Functions  
Basic usage  
template<class vec_t , class mat_t >  
void  set_data (size_t sizex, size_t sizey, const vec_t &x_fun, const vec_t &y_fun, const mat_t &udata) 
Set the data. More...  
template<class mat_t >  
void  set_data (const uniform_grid< double > &ugx, const uniform_grid< double > &ugy, const mat_t &udata) 
Set the data. More...  
template<class vec_t >  
void  set_levels (size_t nlevels, vec_t &ulevels) 
Set the contour levels. More...  
void  calc_contours (std::vector< contour_line > &clines) 
Calculate the contours. More...  
Regrid function  
void  regrid_data (size_t xfact, size_t yfact, size_t interp_type=o2scl::itp_cspline) 
Regrid the data. More...  
Obtain internal data  
void  get_data (size_t &sizex, size_t &sizey, ubvector *&x_fun, ubvector *&y_fun, ubmatrix *&udata) 
Get the data. More...  
void  get_edges (std::vector< edge_crossings > &x_edges, std::vector< edge_crossings > &y_edges) 
Return the edges for each contour level. More...  
void  print_edges_yhoriz (edge_crossings &xedges, edge_crossings &yedges) 
Print out the edges to cout.  
void  print_edges_xhoriz (edge_crossings &xedges, edge_crossings &yedges) 
Print out the edges to cout.  
Public Attributes  
int  verbose 
Verbosity parameter (default 0) More...  
double  lev_adjust 
(default )  
bool  debug_next_point 
If true, debug the functions which determine the next point functions (default false)p.  
Static Public Attributes  
Edge status  
static const int  empty =0 
static const int  edge =1 
static const int  contourp =2 
static const int  endpoint =3 
Protected Member Functions  
int  find_next_point_y_direct (int j, int k, int &jnext, int &knext, int &dir_next, int nsw, edge_crossings &xedges, edge_crossings &yedges) 
Find next point starting from a point on a right edge.  
int  find_next_point_x_direct (int j, int k, int &jnext, int &knext, int &dir_next, int nsw, edge_crossings &xedges, edge_crossings &yedges) 
Find next point starting from a point on a bottom edge.  
void  find_intersections (size_t ilev, double &level, edge_crossings &xedges, edge_crossings &yedges) 
Find all of the intersections of the edges with the contour level.  
void  edges_in_y_direct (double level, interp< ubvector > &si, edge_crossings &yedges) 
Interpolate all right edge crossings.  
void  edges_in_x_direct (double level, interp< ubvector > &si, edge_crossings &xedges) 
Interpolate all bottom edge crossings.  
void  process_line (int j, int k, int dir, std::vector< double > &x, std::vector< double > &y, bool first, edge_crossings &xedges, edge_crossings &yedges) 
Create a contour line from a starting edge.  
void  check_data () 
Check to ensure the x and yarrays are monotonic.  
Protected Attributes  
std::vector< edge_crossings >  yed 
Right edge list.  
std::vector< edge_crossings >  xed 
Bottom edge list.  
Userspecified data  
int  nx 
int  ny 
ubvector  xfun 
ubvector  yfun 
ubmatrix  data 
Userspecified contour levels  
int  nlev 
ubvector  levels 
bool  levels_set 
Static Protected Attributes  
Edge direction  
static const int  dxdir =0 
static const int  dydir =1 
Edge found or not found  
static const int  efound =1 
static const int  enot_found =0 
Private Member Functions  
contour (const contour &)  
contour &  operator= (const contour &) 
Basic Usage
The contours are generated as a series of x and ycoordinates, defining a line. If the contour is closed, then the first and the last set of coordinates will be equal.
The convention used by this class is that the first (row) index of the matrix enumerates the x coordinate and that the second (column) index enumerates the y coordinate. See the discussion in the User's guide in the section called Rows and columns vs. x and y.
The data is copied by set_data(), so changing the data will not change the contours unless set_data() is called again. The functions set_levels() and calc_contours() can be called several times for the same data without calling set_data() again.
Note that in order to simplify the algorithm for computing contour lines, the calc_contours() function will sometimes adjust the userspecified contour levels slightly in order to ensure that no contour line passes exactly through any data point on the grid. The contours are adjusted by multiplying the original contour level by 1 plus a small number ( by default), which is specified in lev_adjust.
Linear interpolation is used to decide whether or not a line segment from the grid and a contour cross. This choice is intentional, since (in addition to making the algorithm much simpler) it is the user (and not this contour class) which is likely best able to refine the data. In case a simple refinement scheme is desired, the method regrid_data() is provided which refines the internally stored data for any interpolation type.
Since linear interpolation is used, the contour calculation implicitly assumes that there is not more than one intersection of any contour level with any line segment. For contours which do not close inside the region of interest, the results will always end at either the minimum or maximum values of the x or y grid points (no extrapolation is ever done). Note also that the points defining the contour are not necessarily equally spaced. Two neighboring points will never be farther apart than the distance across opposite corners of one cell in the grid.
The Algorithm:
This works by viewing the data as defining a square twodimensional grid. The function calc_contours() exhaustively enumerates every line segment in the grid which involves a level crossing and then organizes the points defined by the intersection of a line segment with a level curve into a full contour line.
void o2scl::contour::calc_contours  (  std::vector< contour_line > &  clines  ) 
clines
is not necessarily equal to the number of levels specified in set_levels().

inline 
This is useful to see how the data has changed after a call to regrid_data().

inline 
The size of y_edges
and x_edges
will both be equal to the number of levels set by set_levels().
void o2scl::contour::regrid_data  (  size_t  xfact, 
size_t  yfact,  
size_t  interp_type = o2scl::itp_cspline 

) 
Use interpolation to refine the data set. This can be called before calc_contours() in order to attempt make the contour levels smoother by providing a smaller grid size. If the original number of data points is , then the new number of data points is
The parameters xfact
and yfact
must both be larger than zero and they cannot both be 1.

inline 
The types vec_t
and mat_t
can be any types which have operator
[] and operator
[][] for array and matrix indexing.
Note that this method copies all of the userspecified data to local storage so that changes in the data after calling this function will not be reflected in the contours that are generated.

inline 
The type mat_t
can be any type which has operator
[][] for matrix indexing.
Note that this method copies all of the userspecified data to local storage so that changes in the data after calling this function will not be reflected in the contours that are generated.

inline 
This is separate from the function calc_contours() so that the user can compute the contours for different data sets using the same levels.
int o2scl::contour::verbose 
If verbose is greater than 0, then adjustments to the contour levels will be output and the contour lines will be output as they are built up from the intersections. If verbose is greater than 1, then all edges will be output. If verbose is greater than 2, a keypress will be required after each contour line is constructed.
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