clConditOmegaCalculator Class Reference

Condit's Relative Neighborhood Density Index (Omega) Calculator Version 1.0. More...

#include <ConditOmegaCalculator.h>

Inheritance diagram for clConditOmegaCalculator:

clBehaviorBase clWorkerBase

List of all members.

Public Member Functions

 clConditOmegaCalculator (clSimManager *p_oSimManager)
 Constructor.
 ~clConditOmegaCalculator ()
 Destructor.
void Action ()
 Calculates Condit's Omega.
void GetData (xercesc::DOMDocument *p_oDoc)
 Does setup for this behavior.

Protected Member Functions

void GetParameterFileData (xercesc::DOMDocument *p_oDoc)
 Reads values from the parameter file and performs setup related to the parameters.
void SetupGrid ()
 Sets up the "Relative Neighborhood Density" grid and registers the data members.
void GetTreeCodes (clTreePopulation *p_oPop)
 Gets the X and Y tree data codes.
void SetUpSearching (clTreePopulation *p_oPop)
 Sets up the structures for searching controls.
void ProcessCell (clTreePopulation *p_oPop, clTree *p_oFirstTree, const int &iX, const int &iY, const int &iNeighX, const int &iNeighY)
 Processes a neighboring cell's trees to find distance pairs.
void ProcessOwnCell (clTree *p_oFirstTree, float *p_fNumTrees, const int &iX, const int &iY)
 Processes a single cell's trees to find distance pairs.

Protected Attributes

clGridBasemp_oGrid
 Grid holding Condit's Omega values for the plot plus each species.
float ** mp_fOmegaValues
 Values holding Condit's Omega for each timestep.
short int ** mp_iGridCodes
 Holds the codes for the "Relative Neighborhood Density" grid.
short int ** mp_iXCodes
 Holds codes for X data member.
short int ** mp_iYCodes
 Holds codes for Y data member.
bool ** mp_bCellsSearched
 Which cells have already been paired the current timestep.
float * mp_fIncs
 Distance increment values - array size is m_iNumIncs.
float * mp_fAnnulusAreas
 Area of each annulus - array size is m_iNumIncs.
float m_fMaxDistance
 The max distance to which to calculate Condit's Omega.
float m_fIncrement
 The distance increment used to step out to the max distance.
int m_iNumIncs
 Number of increments for which to calculate Condit's Omega.
int m_iNumXToSearch
 The number of cells to search in the X direction - if the plot is a rectangle and the search distance is long the distances along the two axes may be different.
int m_iNumYToSearch
 The number of cells to search in the Y direction - if the plot is a rectangle and the search distance is long the distances along the two axes may be different.
int m_iNumXCells
 Number of tree population grid cells in X direction.
int m_iNumYCells
 Number of tree population grid cells in Y direction.
short int m_iNumTotalSpecies
 Total number of species.

Friends

class clTestConditOmegaCalculator


Detailed Description

Condit's Relative Neighborhood Density Index (Omega) Calculator Version 1.0.

This behavior calculates Condit's relative neighborhood density index (omega). This index measures the aggregation of species. It is calculated for successive distances out to a maximum. The user sets the maximum distance and the increment. Omega for a species for a given distance x + Δx is calculated as:

Ω = (ΣNx / (T * Ax))/den

where Ax is the area of the annulus described by the radii x and Δx , in square meters, Nx is the number of conspecific neighbors of trees between x and Δx , T is the total number of trees of that species in the plot, and den is the species density in the plot.

In other words, Ω is the average density of conspecific neighbors at a specific distance divided by the plot's density of that species. Saplings and adults are counted as neighbors. All other types are ignored.

Conceptually, the way to carry out this search is to take each tree, find the density of its conspecific neighbors between each pair of radii x and Δx , average those values by species, and divide by the plot density for each species. In practice I can use a quicker method. The search proceeds by tree population grid cell. For each cell, a square of cells around it is searched. A matrix is used to keep track of which cells have already been paired so they are not paired again. Each pair of conspecifics is counted into the appropriate distance bucket (twice, once for when each tree is acting as a neighbor to the other's target). Then these buckets are used to calculate Ω according to the formula above.

The statistic is calculated for all individual species.

The values are collected into a grid called "Relative Neighborhood Density".

This class's namestring and parameter file call string is "Condit's Omega". Any tree type/species assignments are ignored.


Edit history:
-----------------
September 18, 2007 - Created (LEM)


Constructor & Destructor Documentation

clConditOmegaCalculator::clConditOmegaCalculator ( clSimManager p_oSimManager  ) 

Constructor.

Parameters:
p_oSimManager clSimManager object.

clConditOmegaCalculator::~clConditOmegaCalculator (  ) 

Destructor.


Member Function Documentation

void clConditOmegaCalculator::Action (  )  [virtual]

Calculates Condit's Omega.

First, the values in the "Relative Neighborhood Density" grid are cleared. Then this moves through the grid cells looking for tree pairs. For each cell this searches cells in a circle, using ProcessCell() and ProcessOwnCell() to find pairs. Once tree pairs have been found, this finishes the Condit's Omega calculation.

Reimplemented from clBehaviorBase.

void clConditOmegaCalculator::GetData ( xercesc::DOMDocument *  p_oDoc  )  [virtual]

Does setup for this behavior.

Calls:

  1. GetParameterFileData()
  2. GetTreeCodes()
  3. SetupGrid()
  4. SetUpSearching()
  5. Action() so that the initial conditions value will be added
Parameters:
p_oDoc DOM tree of parsed input file.

Implements clWorkerBase.

void clConditOmegaCalculator::GetParameterFileData ( xercesc::DOMDocument *  p_oDoc  )  [protected]

Reads values from the parameter file and performs setup related to the parameters.

This validates the increment and distance.

Parameters:
p_oDoc DOM tree of parsed input file.
Exceptions:
modelErr if either the increment or the max distance are less than or equal to zero, or if the increment is less than the max distance.

void clConditOmegaCalculator::SetupGrid (  )  [protected]

Sets up the "Relative Neighborhood Density" grid and registers the data members.

void clConditOmegaCalculator::GetTreeCodes ( clTreePopulation p_oPop  )  [protected]

Gets the X and Y tree data codes.

Parameters:
p_oPop Tree population object

void clConditOmegaCalculator::SetUpSearching ( clTreePopulation p_oPop  )  [protected]

Sets up the structures for searching controls.

This sets up the mp_bCellsSearched matrix and finds the search distances in the X and Y directions. If the search distance is more than half the plot length in either direction, then it will be limited to half the plot length. This also sets up the mp_fIncs and mp_fAnnulusAreas arrays.

Parameters:
p_oPop Tree population object

void clConditOmegaCalculator::ProcessCell ( clTreePopulation p_oPop,
clTree p_oFirstTree,
const int &  iX,
const int &  iY,
const int &  iNeighX,
const int &  iNeighY 
) [protected]

Processes a neighboring cell's trees to find distance pairs.

This finds all pairs of conspecific saplings and adults within the max distance and counts each pair into the appropriate bin in the Condit's Omega calculator array. Each pair is counted in twice (once for each tree acting as the other's neighbor).

Parameters:
p_oPop Tree population object.
p_oFirstTree The shortest valid tree in the home cell.
iX X coordinate of home cell.
iY Y coordinate of home cell.
iNeighX X coordinate of the neighbor cell to search for tree pairs.
iNeighY Y coordinate of the neighbor cell to search for tree pairs.

void clConditOmegaCalculator::ProcessOwnCell ( clTree p_oFirstTree,
float *  p_fNumTrees,
const int &  iX,
const int &  iY 
) [protected]

Processes a single cell's trees to find distance pairs.

This finds all pairs of conspecific saplings and adults within the max distance, being careful not to pair a tree with itself, and counts each pair into the appropriate bin in the Condit's Omega calculator array. Each pair is counted in twice (once for each tree acting as the other's neighbor). This also counts all the trees in the cell for the purposes of finding the plot's density.

Parameters:
p_oFirstTree The shortest valid tree in the home cell.
p_fNumTrees The array for number of saplings and adults in the cell for each species.
iX X coordinate of home cell.
iY Y coordinate of home cell.


Friends And Related Function Documentation

friend class clTestConditOmegaCalculator [friend]


Member Data Documentation

Grid holding Condit's Omega values for the plot plus each species.

The grid name is "Relative Neighborhood Density". It has one data member for each increment step out to the max for each species. The names are X_Y, where X is the increment step number (starting at zero) and Y is the species number (starting at zero). It also has two more for the length of distance increment ("inc") and the max distance ("dist"), to make output display easier.

Values holding Condit's Omega for each timestep.

Array size is number of species by m_iNumIncs.

short int** clConditOmegaCalculator::mp_iGridCodes [protected]

Holds the codes for the "Relative Neighborhood Density" grid.

The first array index is number of species, with array size being m_iNumTotalSpecies. The second array index is buckets for values along the distance line, and is sized m_iNumIncs.

short int** clConditOmegaCalculator::mp_iXCodes [protected]

Holds codes for X data member.

First array index is total # species, second is number types (2 - sapling, adult).

short int** clConditOmegaCalculator::mp_iYCodes [protected]

Holds codes for Y data member.

First array index is total # species, second is number types (2 - sapling, adult).

Which cells have already been paired the current timestep.

The matrix size is number of total cells by number of total cells (flattening the 2D tree population cell matrix into a single array). The index for a tree population grid cell is number of X cells * X cell index + Y cell index. Since every grid cell is paired with every other, once a pair of grid cells is searched, two matrix cells must be switched to true.

Distance increment values - array size is m_iNumIncs.

Area of each annulus - array size is m_iNumIncs.

The max distance to which to calculate Condit's Omega.

The distance increment used to step out to the max distance.

Number of increments for which to calculate Condit's Omega.

The number of cells to search in the X direction - if the plot is a rectangle and the search distance is long the distances along the two axes may be different.

The number of cells to search in the Y direction - if the plot is a rectangle and the search distance is long the distances along the two axes may be different.

Number of tree population grid cells in X direction.

Number of tree population grid cells in Y direction.

Total number of species.

For the destructor.


The documentation for this class was generated from the following file:

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