jitterDupCoords: Jitters (duplicated) coordinates.

Description

Jitters 2D coordinates uniformily on a region around (duplicated) points.

Usage

jitter2d(coords, max, min = 0.2 * max, fix.one = TRUE,
         which.fix = c("random", "first", "last")) 
jitterDupCoords(x, ...)
# S3 method for default
jitterDupCoords(x, ...)
# S3 method for geodata
jitterDupCoords(x, ...)

Value

jitter2d returns an object of the same type fo the input with jittered values

jitterDupCoords returns an object of the same type fo the input with jittered coordinate values only at the duplicated locations

Arguments

x, coords: a matrix or data frame with 2D coordinates or geodata object.
max: numeric scalar defining maximum jittering distance.
min: numeric scalar defining minimum jittering distance.
fix.one: logical. Whether or not one of the coordinates should not be jittered.
which.fix: single element vector of integer or character, defining which coordinate won't be jittered. Only used if fix.one=TRUE.
...: arguments passed to jitter2d.

Author

Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br,
Peter J. Diggle p.diggle@lancaster.ac.uk.

Examples

Run this code

## simulating data
dt <- grf(30, cov.p=c(1, .3)) 
dt$coords <- round(dt$coords, dig=2)
## "forcing" some duplicated locations
dt$coords[4,] <- dt$coords[14,] <- dt$coords[24,] <- dt$coords[2,]
dt$coords[17,] <- dt$coords[23,] <- dt$coords[8,]

## jittering a matrix of duplicated coordinates
dt$coords[c(2,4,14,24),]
jitter2d(dt$coords[c(2,4,14,24),], max=0.01)

## jittering only the duplicated locations and comparing with original
cbind(dt$coords, jitterDupCoords(dt$coords, max=0.01))

## creating a now geodata object jittering the duplicated locations of the original one:
dup.coords(dt)
dt1 <- jitterDupCoords(dt, max=0.01)
dup.coords(dt1)