ConnCompLabel {SDMTools} | R Documentation |
ConnCompLabel
is a 1 pass implementation of
connected components labelling. Here it is applied to
identify disjunt patches within a distribution.
The
raster matrix can be a raster of class 'asc' (adehabitat
package), 'RasterLayer' (raster package) or
'SpatialGridDataFrame' (sp package).
ConnCompLabel(mat)
mat |
is a binary matrix of data with 0 representing background and 1 representing environment of interest. NA values are acceptable. The matrix can be a raster of class 'asc' (this & adehabitat package), 'RasterLayer' (raster package) or 'SpatialGridDataFrame' (sp package) |
A matrix of the same dim and class of mat
in which
unique components (individual patches) are numbered 1:n
with 0 remaining background value.
Jeremy VanDerWal jjvanderwal@gmail.com
Chang, F., C.-J. Chen, and C.-J. Lu. 2004. A linear-time component-labeling algorithm using contour tracing technique. Comput. Vis. Image Underst. 93:206-220.
#define a simple binary matrix tmat = { matrix(c( 0,0,0,1,0,0,1,1,0,1, 0,0,1,0,1,0,0,0,0,0, 0,1,NA,1,0,1,0,0,0,1, 1,0,1,1,1,0,1,0,0,1, 0,1,0,1,0,1,0,0,0,1, 0,0,1,0,1,0,0,1,1,0, 1,0,0,1,0,0,1,0,0,1, 0,1,0,0,0,1,0,0,0,1, 0,0,1,1,1,0,0,0,0,1, 1,1,1,0,0,0,0,0,0,1),nr=10,byrow=TRUE) } #do the connected component labelling ccl.mat = ConnCompLabel(tmat) ccl.mat image(t(ccl.mat[10:1,]),col=c('grey',rainbow(length(unique(ccl.mat))-1)))