hexbin

0th

Percentile

Bivariate Binning into Hexagon Cells

Creates a "hexbin" object. Basic components are a cell id and a count of points falling in each occupied cell.

Basic methods are show(), plot() and summary(), but also erode.

Keywords
dplot
Usage
hexbin(x, y, xbins = 30, shape = 1,
       xbnds = range(x), ybnds = range(y),
       xlab = NULL, ylab = NULL, IDs = FALSE)
Arguments
x, y
vectors giving the coordinates of the bivariate data points to be binned. Alternatively a single plotting structure can be specified: see xy.coords. NA's are allowed and silently omitted.
xbins
the number of bins partitioning the range of xbnds.
shape
the shape = yheight/xwidth of the plotting regions.
xbnds, ybnds
horizontal and vertical limits of the binning region in x or y units respectively; must be numeric vector of length 2.
xlab, ylab
optional character strings used as labels for x and y. If NULL, sensible defaults are used.
IDs
logical indicating if the individual cell IDs should be returned, see also below.
Details

Returns counts for non-empty cells only. The plot shape must be maintained for hexagons to appear with equal sides. Some calculations are in single precision.

Note that when plotting a hexbin object, the grid package is used. You must use its graphics (or those from package lattice if you know how) to add to such plots.

Value

  • an S4 object of class "hexbin". It has the following slots:
  • cellvector of cell ids that can be mapped into the (x,y) bin centers in data units.
  • countvector of counts in the cells.
  • xcmThe x center of mass (average of x values) for the cell.
  • ycmThe y center of mass (average of y values) for the cell.
  • xbinsnumber of hexagons across the x axis. hexagon inner diameter =diff(xbnds)/xbins in x units
  • shapeplot shape which is yheight(inches) / xwidth(inches)
  • xbndsx coordinate bounds for binning and plotting
  • ybndsy coordinate bounds for binning and plotting
  • dimenThe i and j limits of cnt treated as a matrix cnt[i,j]
  • nnumber of (non NA) (x,y) points, i.e., sum(* @count).
  • ncellsnumber of cells, i.e., length(* @count), etc
  • callthe function call.
  • xlab, ylabcharacter strings to be used as axis labels.
  • cIDof class, "integer or NULL", only if IDs was true, an integer vector of length n where cID[i] is the cell number of the i-th original point (x[i], y[i]). Consequently, the cell and count slots are the same as the names and entries of table(cID), see the example.

References

Carr, D. B. et al. (1987) Scatterplot Matrix Techniques for Large $N$. JASA 83, 398, 424--436.

See Also

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

Aliases
  • hexbin
  • hexbin-class
  • integer or NULL-class
  • show,hexbin-method
  • summary,hexbin-method
Examples
set.seed(101)
x <- rnorm(10000)
y <- rnorm(10000)
(bin <- hexbin(x, y))
## or
plot(hexbin(x, y + x*(x+1)/4),
     main = "(X, X(X+1)/4 + Y)  where X,Y ~ rnorm(10000)")

## Using plot method for hexbin objects:
plot(bin, style = "nested.lattice")

hbi <- hexbin(y ~ x, xbins = 80, IDs= TRUE)
str(hbi)
tI <- table(hbi@cID)
stopifnot(names(tI) == hbi@cell,
                tI  == hbi@count)

## NA's now work too:
x[runif(6, 0, length(x))] <- NA
y[runif(7, 0, length(y))] <- NA
hbN <- hexbin(x,y)
summary(hbN)
Documentation reproduced from package hexbin, version 1.29.0, License: GPL-2

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