index.to.rowcol {CTFS} | R Documentation |
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
.
index.to.rowcol(index, gridsize = 20, plotdim = c(1000, 500))
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 |
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).
Returns a data frame of row and column numbers. Returns NA when an invalid gx or gy value is given.
Rick Condit, Suzanne Lao and Pamela Hall
## Not run: index.to.rowcol(45) tst.index=c(0,25,1226,1250) index.to.rowcol(tst.index) row col ## End(Not run)