shiftpoints: Calculate a shift for plotting overlapping points
Description
Calculate a shift to add to overlapping points in plots for better visibility
Usage
shiftpoints(x, y, sh=( max(x)-min(x))/100, centered=TRUE, method=1, reg=6,
na.rm=TRUE)
Arguments
x
a data matrix or numeric vector for use in a plot.
y
a data matrix or numeric vector for use in a plot.
sh
the maximum total shift.
centered
logical, whether the shift is centered at 0, if FALSE
the shift will be positive only.
method
numeric, can have the value 1 or 2, see Details.
reg
numeric, see Details.
na.rm
logical, indicating whether missing values should be removed.
Value
Returns an array of shift values with the same dimension
as x.
Details
This function is similar to jitter but is defines for points in
a two-dimensional plot. In contrast to jitter only the points with ties
have a shift different from 0. The method to calculate the shift is therefore
not based on random numbers.
If method=1 (default) the individual shift will be selected so that the
shift range is sh, without regard of the number of overlapping points
method=2 means that for up to reg overlapping values a fixed
shift of sh/reg is used