gxgy.to.rowcol {CTFS} | R Documentation |
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
.
gxgy.to.rowcol(gx, gy, gridsize = 20, plotdim = c(1000, 500))
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 |
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 is given.
Rick Condit, Suzanne Lao and Pamela Hall
## 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)