Description Usage Arguments Details Value Author(s) See Also Examples
View source: R/AllGeneric.R View source: R/untie.R
This is a generic function intended to randomly break tied data in a
way similar to what jitter
does: tiebreaking is
performed by shifting all data points by a random amount.
The surveillance package defines methods for matrices,
"epidataCS"
, and a default method for numeric vectors.
1 2 3 4 5 6 7 8 9 10 11 12 13  untie(x, amount, ...)
## S3 method for class 'epidataCS'
untie(x, amount = list(t=NULL, s=NULL),
minsep = list(t=0, s=0), direction = "left", keep.sources = FALSE,
..., verbose = FALSE)
## S3 method for class 'matrix'
untie(x, amount = NULL, minsep = 0,
constraint = NULL, giveup = 1000, ...)
## Default S3 method:
untie(x, amount = NULL, minsep = 0,
direction = c("symmetric", "left", "right"), sort = NULL,
giveup = 1000, ...)

x 
the data to be untied. 
amount 
upper bound for the random amount by which data are shifted.

minsep 
minimum separation of jittered points. Can only be
obeyed if much smaller than 
keep.sources 
logical ( 
constraint 
an object of class 
giveup 
number of attempts after which the algorithm should stop trying to generate new points. 
direction 
one of 
sort 
logical indicating if the jittered vector should be sorted. Defaults to doing so if the original vector was already sorted. 
... 
For the 
verbose 
logical passed to 
For numeric vectors (default method), the jittered version is the
same as for jitter(x, amount=amount)
, if
direction="symmetric"
(and amount
is nonNULL
),
and otherwise uses
x
“+” runif(length(x), 0, amount)
.
For matrices, a vector uniformly drawn from the disc with radius
amount
is added to each point (row).
For "epidataCS"
, amount
is a list stating the amounts
for the temporal and/or spatial dimension, respectively. It then
uses the specific methods with arguments constraint=x$W
,
direction
, and sort=TRUE
. Note that this implements a
simplistic approach of tiebreaking where all events are assumed to be
subject to the same amounts of censoring, and the default amounts may
not be sensible choices.
the untied (jittered) data.
Sebastian Meyer
1 2 3 4 5 6 7 8 9 10 11 12 13  # vector example
set.seed(123)
untie(c(rep(1,3), rep(1.2, 4), rep(3,3)), direction="left", sort=FALSE)
# spatial example
data(imdepi)
coords < coordinates(imdepi$events)
table(duplicated(coords))
plot(coords, cex=sqrt(multiplicity(coords)))
set.seed(1)
coords_untied < untie(coords)
stopifnot(!anyDuplicated(coords_untied))
points(coords_untied, col=2) # shifted by very small amount in this case

Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.