CTFS.quadfunctions {CTFS} | R Documentation

## Overview of Functions that provide Information on the location of trees in a Plot

### Description

A series of functions that convert from one form of location to another, such as from a tree coordinate (gx, gy) to a quadrate, from a quadrate to a row and col index, etc.

### Details

FUNCTIONS FOR CONVERTING AMONG INDEX, COORDINATES AND QUADRATES

`rowcol.to.index` | Converts a Row and Column to a Quadrate Number
`index.to.rowcol` | Converts a Quadrate Number (Indext) to Row and Column Numbers
`gxgy.to.index` | Converts GX GY Coordinates to a Quadrate Number
`index.to.gxgy` | Converts a Quadrate Number to GX GY Coordinates
`gxgy.to.rowcol` | Converts a GX GY Coordinates to Row and Column Numbers
`gxgy.to.hectindex` | Converts GX GY Coordinates to a Hectare Number
`findborderquads` | Returns Indices of Neighboring Quadrats Given a Quadrat Index

PLOT LAYOUT

The standard plot is 1000 by 500 m, running West to East and South to North, like the conventional cooridnates of a graph.

The 0,0 corner and edge going from 0,0 to 0,500 and going from 0,0 to 1000,0 are included in the plot. The outer edges, going from 500,0 to 1000,500 and 1000,0 to 1000,500 are NOT included in the plot. This holds true for any portion of the plot.

Therefore, hectare 1 includes the sides 0,0 to 0,100 and 0,0 to 100,0 but NOT 100,0 to 100,100 and 100,0 to 100,100.
Quadrate 1 includes sides 0,0 to 0,20 and 0,0 to 20, 0 but NOT 20,0 to 20,20 and 0,20 to 20,20.

The convention is 20 by 20 m quadrates, 1250 of them in a 1000 by 500 m plot. The convention is to number the quadrates starting in the southwest corner and going northward up a "column" of 25, and returning to the southern border for 26-50, etc:

These function should work for any 4 sided plot, square or rectangular. But the dimension of the plot if different from 1000, 500 must be provided for each function.

Quadrate Number, Index

25 | 50 | 75 ... | 1250
24 | 49 | 74 ... | 1249
. | . | . ... | .
. | . | . ... | .
. | . | . ... | .
3 | 28 | 53 ... | 1228
2 | 27 | 52 ... | 1227
1 | 26 | 51 ... | 1226

Rows and Columns

cols

1 | 2 | 3 ... | 48 | 49 | 50

rows

25 | ...
24 | ...
. | ...
. | ...
. | ...
2 | ...
1 | ...

Hectare Number, Index

5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50
4 | 9 | 14 | 19 | 24 | 29 | 34 | 39 | 44 | 49
3 | 8 | 13 | 18 | 23 | 28 | 33 | 38 | 43 | 48
2 | 7 | 12 | 17 | 22 | 27 | 32 | 37 | 42 | 47
1 | 6 | 11 | 16 | 21 | 26 | 31 | 36 | 41 | 46

DEFINITIONS

index
  quadrate number, default 1 to 1250
gxgy
  coordinates (m) of a tree relative to plot dimensions, gx determines the column number and gy determines the row number
rowcol
  row and column number when viewing plot as a rectangular matrix with quadrate 1 in lower left corner. This is NOT the usual visual layout of a mathematical matrix, see above
hectindex
  hectare number, default 1 to 50
plotdim
  dimensions of plot in m, x then y. The default is `plotdim=c(1000,500)`
gridsize
  dimensions of the gridsize, quadrates or hectares in most cases. The default is `gridsize=20` for a quadrate and `gridsize=100` for a hectare

`gxgy.to.hectindex` has a fixed `gridsize=100` but it gives the same result as using `gxgy.to.index` with `gridsize=100`.

EXAMPLES

Examples of how to use these functions, showing the relationship between index, rowcol, gxgy, and hectindex.

     index.to.rowcol(43)
        row col
     1  18   2
     index.to.gxgy(43)
       gx  gy
     1 20 340
     gxgy.to.index(20,340)
     [1] 43
     rowcol.to.index(18,2)
     [1] 43
     gxgy.to.rowcol(20,340)
        row col
     1  18   2
     gxgy.to.hectindex(20,340)
     [1] 4

     gxgy.to.index(1000,500)
     [1] NA

### Author(s)

Rick Condit, Suzanne Lao and Pamela Hall

### See Also

`CTFS.groupcats`, `CTFS.readwrite`, `CTFS.utilities`

[Package CTFS version 1.00 Index]