gxgy.to.rowcol {CTFS} | R Documentation

## Converts a GX GY Coordinates to Row and Column Numbers

### Description

This functions takes gx gy tree coordinate position and identifies the row and column numbers in which it is located. The row and column numbers are based on a gridsize that by default divides the plot into 20 by 20 m squares. The gridsize can be defined by the user so other quadrate sizes can be used. The inverse function is `rowcol.to.gxgy`.

### Usage

    gxgy.to.rowcol(gx, gy, gridsize = 20, plotdim = c(1000, 500))

### Arguments

`gx` | tree x coordinate
`gy` | tree y coordinate
`gridsize` | side of the square quadrate, 20 x 20m by default
`plotdim` | dimensions of the plot: east-west 1000m and north-south 500m

### Details

The function should work for any 4 sided plot, square or rectangular. 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. The columns are numbered 1 to 50, west to east (left to right). The rows are numbered 1 to 25, south to north (bottom to top).

### Value

Returns a data frame of row and column numbers. Returns NA when an invalid gx or gy is given.

### Author(s)

Rick Condit, Suzanne Lao and Pamela Hall

### See Also

`CTFS.quadfunctions`

### Examples

    ## Not run:
    tst.gy=c(0,499,0,499)
    tst.gx=c(0,0,999,999)
    gxgy.to.rowcol(tst.gx,tst.gy)

    # the far edges of the plot are out of bounds
    tst.gx=c(0,0,1000,1000)
    tst.gy=c(0,500,0,500)
    gxgy.to.rowcol(tst.gx,tst.gy)
    ## End(Not run)

[Package CTFS version 1.00 Index]