hexbin

From hexbin v1.29.0 by Nicholas LewinKoh

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.

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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