| jitter {base} | R Documentation |
‘Jitter’ (Add Noise) to Numbers
Description
Add a small amount of noise to a numeric vector.
Usage
jitter(x, factor = 1, amount = NULL)
Arguments
x |
numeric vector to which jitter should be added. |
factor |
numeric. |
amount |
numeric; if positive, used as amount (see below),
otherwise, if Default ( |
Details
The result, say r, is r <- x + runif(n, -a, a)
where n <- length(x) and a is the amount
argument (if specified).
Let z <- max(x) - min(x) (assuming the usual case).
The amount a to be added is either provided as positive
argument amount or otherwise computed from z, as
follows:
If amount == 0, we set a <- factor * z/50 (same as S).
If amount is NULL (default), we set
a <- factor * d/5 where d is the smallest
difference between adjacent unique (apart from fuzz) x values.
Value
jitter(x, ...) returns a numeric of the same length as
x, but with an amount of noise added in order to break
ties.
Author(s)
Werner Stahel and Martin Maechler, ETH Zurich
References
Chambers, J. M., Cleveland, W. S., Kleiner, B. and Tukey, P.A. (1983) Graphical Methods for Data Analysis. Wadsworth; figures 2.8, 4.22, 5.4.
Chambers, J. M. and Hastie, T. J. (1992) Statistical Models in S. Wadsworth & Brooks/Cole.
See Also
rug which you may want to combine with jitter.
Examples
round(jitter(c(rep(1, 3), rep(1.2, 4), rep(3, 3))), 3)
## These two 'fail' with S-plus 3.x:
jitter(rep(0, 7))
jitter(rep(10000, 5))