Add a small amount of noise to a numeric vector.
jitter(x, factor = 1, amount = NULL)
amount == 0, we set
a <- factor * z/50 (same as S).
NULL (default), we set
a <- factor * d/5 where d is the smallest difference between adjacent unique (apart from fuzz)
jitter(x, ...) returns a numeric of the same length as
x, but with an
amount of noise added in order to break ties.
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.
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