index.to.rowcol {CTFS} | R Documentation

## Converts a Quadrate Number (Indext) to Row and Column Numbers

### Description

This functions takes a quadrate number (index) 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.index`.

### Usage

    index.to.rowcol(index, gridsize = 20, plotdim = c(1000, 500))

### Arguments

`index` | quadrate, valid default values 1 to 1250
`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 value is given.

### Author(s)

Rick Condit, Suzanne Lao and Pamela Hall

### See Also

`CTFS.quadfunctions`

### Examples

    ## Not run:
    index.to.rowcol(45)

    tst.index=c(0,25,1226,1250)
    index.to.rowcol(tst.index)
      row col
    ## End(Not run)

[Package CTFS version 1.00 Index]