COGravity {SDMTools} | R Documentation |
COGravity
calculates the Centre of Gravity (or also
known as Centre of Mass) for point or raster spatial
data.
Note: NA data is automatically ommitted
from analysis.
COGravity(x, y = NULL, z = NULL, wt = NULL)
x |
a vector of e.g., longitudes or eastings, or a raster of class 'asc', 'RasterLayer' or 'SpatialGridDataFrame'. |
y |
a vector of e.g., latitudes or northings. |
z |
a vector of e.g., elevations. |
wt |
a vector or raster of class 'asc', 'RasterLayer' or 'SpatialGridDataFrame' representing weights for data. |
For raster-based data, if wt
is missing, the values
of the ascii are assumed to be the weights; otherwise, the
values are assumed to be the z
values.
Returns a named vector of data representing the Centre of Gravity in x, y & z dimensions (depending on data supplied).
Jeremy VanDerWal jjvanderwal@gmail.com
#create some points x = seq(154,110,length=25) y = seq(-10,-54,length=25) z = seq(100,200,length=25) wt = runif(25) #random weights #calculate the Centre of Gravity for these points COGravity(x,y,z,wt) #create a simple objects of class 'asc' x = as.asc(matrix(1:50,nr=50,nc=50)) wt = as.asc(matrix(runif(50),nr=50,nc=50)) #calculate COG with weighting defined in x COGravity(x) #calculate COG with weighting defined in wt (values in x are assumed elevation (z)) COGravity(x,wt=wt)