Erosion of a Hexagon Count Image

This erosion algorithm removes counts from hexagon cells at a rate proportional to the cells' exposed surface area. When a cell becomes empty, algorithm removes the emptied cell and notes the removal order. Cell removal increases the exposure of any neighboring cells. The last cell removed is a type of bivariate median.

erode(hbin, cdfcut = 0.5)
erode.hexbin(hbin, cdfcut = 0.5)

an object of class hexbin.


number in (0,1) indicating the confidence level for the limits.


The algorithm extracts high count cells with containing a given fraction (cdfcut) of the total counts. The algorithm extracts all cells if cdfcut=0. The algorithm performs gray-level erosion on the extracted cells. Each erosion cycle removes counts from cells. The counts removed for each cell are a multiple of the cell's exposed-face count. The algorithm choses the multiple so at least one cell will be empty or have a count deficit on each erosion cycle. The erode vector contain an erosion number for each cell. The value of erode is

6*erosion\_cycle\_ at\_ cell\_ removal - cell\_deficit\_at\_removal

Cells with low values are eroded first. The cell with the highest erosion number is a candidate bivariate median. A few ties in erode are common.


An "erodebin" object (with all the slots from hbin) and additionally with high count cells and a component erode that gives the erosion order.

See Also

hexbin, smooth.hexbin, hcell2xy, gplot.hexbin, grid.hexagons, grid.hexlegend

  • erode
  • erode.hexbin
  • erode,hexbin-method
  • erodebin-class
library(hexbin) # NOT RUN { set.seed(153) x <- rnorm(10000) y <- rnorm(10000) bin <- hexbin(x,y) smbin <- smooth.hexbin(bin) erodebin <- erode.hexbin(smbin, cdfcut=.5) plot(erodebin) ## bivariate boxplot hboxplot(erodebin, main = "hboxplot(erodebin)") # } # NOT RUN { <!-- %% MM: This looks wrong -- both the graphic and the logic in "par" here : --> # } # NOT RUN { # show erosion order plot(bin,style= "lat", minarea=1, maxarea=1, legend=FALSE, border=gray(.7)) # } # NOT RUN { <!-- %% FIXME: {compare with example in "hexbin0"} --> # } # NOT RUN { grid.hexagons(erodebin,style= "lat", minarea=1, maxarea=1,pen="green") xy <- hcell2xy(erodebin) library("grid") grid.text(lab = as.character(erodebin@erode), xy$x, xy$y, gp = gpar(col="white", cex=0.65)) # }
Documentation reproduced from package hexbin, version 1.27.1, License: GPL-2

Community examples

Looks like there are no examples yet.