gxgy.to.hectindex {CTFS} | R Documentation

## Converts GX GY Coordinates to a Hectare Number

### Description

This function takes an x, y plot location and identifies the hectare number. The far edges of the plot is considered out-of-bounds. The same results can be obtained by using a gridsize of 100 by 100 with the function `gxgy.to.index`.

### Usage

    gxgy.to.hectindex(gx, gy, plotdim = c(1000, 500))

### Arguments

`gx` | tree x coordinate
`gy` | tree y coordinate
`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 to number the hectares starting in the southwest corner and going northward up a "column" of 5, and returning to the southern border for 6-10, etc.

### Value

Returns a vector, the hectare number (default values range from 1 to 50). Returns a -1 when an invalid gx or gy value 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.hectindex(tst.gx,tst.gy)

    # the same values can be obtained using gxgy.to.index with a gridsize
    of 100
    gxgy.to.hectindex(783,456)

    gxgy.to.index(783,456,gridsize=100)
    ## End(Not run)

[Package CTFS version 1.00 Index]