shuffle-utils | R Documentation |
Unrestricted and restricted permutations for time series, line transects, spatial grids and blocking factors.
shuffleFree(x, size) shuffleSeries(x, mirror = FALSE, start = NULL, flip = NULL) shuffleGrid(nrow, ncol, mirror = FALSE, start.row = NULL, start.col = NULL, flip = NULL) shuffleStrata(strata, type, mirror = FALSE, start = NULL, flip = NULL, nrow, ncol, start.row = NULL, start.col = NULL)
x |
vector of indices to permute. |
size |
number of random permutations required |
mirror |
logical; should mirroring of sequences be allowed? |
start |
integer; the starting point for time series permutations. If missing, a random starting point is determined. |
flip |
logical, length 1 ( |
nrow, ncol |
numeric; the number of rows and columns in the grid. |
start.row, start.col |
numeric; the starting row and column for the shifted grid permutation. If non supplied, a random starting row and column will be selected. |
strata |
factor; the blocks to permute. |
type |
character; the type of permutation used to shuffle the
|
These are developer-level functions for generating permuted indexes from one of several restricted and unrestricted designs.
shuffleFree
is a wrapper to code underlying
sample
, but without the extra over head of sanity
checks. It is defined as sample.int(x, size, replace = FALSE)
.
You must arrange for the correct values to be supplied, where
x
is a vector of indices to sample from, and size
is the
number of indices to sample. Sampling is done without replacement and
without regard to prior probabilities. Argument size
is allowed
so that one can draw a single observation at random from the indices
x
. In general use, size
would be set equal to
length{x}
.
A integer vector of permuted indices.
Gavin Simpson
check
, a utility function for checking
permutation scheme described by
how
. shuffle
as a user-oriented
wrapper to these functions.
set.seed(3) ## draw 1 value at random from the set 1:10 shuffleFree(1:10, 1) ## permute the series 1:10 x <- 1:10 shuffleSeries(x) ## with random starting point shuffleSeries(x, start = 5L) ## known starting point shuffleSeries(x, flip = TRUE) ## random start, forced mirror shuffleSeries(x, mirror = TRUE) ## random start, possibly mirror ## permute a grid of size 3x3 shuffleGrid(3, 3) ## random starting row/col shuffleGrid(3, 3, start.row = 2, start.col = 3) ## with known row/col shuffleGrid(3, 3, flip = rep(TRUE, 2)) ## random start, forced mirror
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