| makeGrid {PBSmapping} | R Documentation |
Makes a grid of polygons, using PIDs and SIDs according
to the input arguments.
makeGrid (x, y, byrow = TRUE, addSID = TRUE, projection = NULL, zone = NULL)
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. |
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
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)).
addPolys,
clipPolys,
combineEvents,
findCells,
findPolys,
PolySet,
thickenPolys.
#--- make a 10 x 10 grid polyGrid <- makeGrid(x=0:10, y=0:10) #--- plot the grid plotPolys(polyGrid, density=0, projection=1)