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 = 0 the default is factor * z/50. Default (NULL): factor * d/5 where d is about the smallest difference between x values.

### 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.

rug which you may want to combine with jitter.
round(jitter(c(rep(1, 3), rep(1.2, 4), rep(3, 3))), 3)