R: Make a Grid of Polygons

makeGrid {PBSmapping}

R Documentation

Make a Grid of Polygons

Description

Make a grid of polygons, using PIDs and SIDs according to the input arguments.

Usage

makeGrid(x,y,byrow=TRUE,addSID=TRUE,projection=NULL,zone=NULL)

Arguments

`x`	vector of X-coordinates (of length m).
`y`	vector of Y-coordinates (of length n).
`byrow`	Boolean value; if `TRUE`, increment `PID` along X.
`addSID`	Boolean value; if `TRUE`, include an `SID` column in the resulting PolySet.
`projection`	optional `projection` attribute to add to the PolySet.
`zone`	optional `zone` attribute to add to the PolySet.

Details

This function makes a grid of polygons, labeling them according to byrow and addSID. In the following description, the variables i and j indicate column and row numbers, respectively, where the lower-left cell of the grid is (1, 1).

byrow = TRUE and addSID = FALSE implies PID = i + (j - 1) * (m - 1)
byrow = FALSE and addSID = FALSE implies PID = j + (i - 1) * (n - 1)
byrow = TRUE and addSID = TRUE implies PID = i, SID = j
byrow = FALSE and addSID = TRUE implies PID = j, SID = i

Value

PolySet with columns PID, SID (if addSID = TRUE), POS, X, and Y. The PolySet is a set of rectangular grid cells with vertices:
(x_i, y_j), (x_(i+1), y_j), (x_(i+1), y_(j+1)), (x_i, y_(j+1)).

Examples

local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- make a 10 x 10 grid
  polyGrid <- makeGrid(x=0:10, y=0:10)
  #--- plot the grid
  plotPolys(polyGrid, density=0, projection=1)
  par(oldpar)
})

[Package PBSmapping version 2.69.76 Index]