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

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]