Description Usage Arguments Details Value Author(s) See Also Examples

`check`

provides checking of permutation schemes for
validity. `permuplot`

produces a graphical representation of the
selected permutation design.

1 2 3 4 |

`object` |
an R object. See Details for a complete description,
especially for |

`control` |
a list of control values describing properties of the
permutation design, as returned by a call to |

`quietly` |
logical; should messages by suppressed? |

`...` |
arguments to other methods. |

`check`

is a utility functions for working with the new
permutation schemes available in `shuffle`

.

`check`

is used to check the current permutation schemes
against the object to which it will be applied. It calculates the
maximum number of possible permutations for the number of observations
in `object`

and the permutation scheme described by
`control`

. The returned object contains component `control`

,
an object of class `"how"`

suitably modified if
`check`

identifies a problem.

The main problem is requesting more permutations than is possible with
the number of observations and the permutation design. In such cases,
`nperm`

is reduced to equal the number of possible permutations,
and complete enumeration of all permutations is turned on
(`control$complete`

is set to `TRUE`

).

Alternatively, if the number of possible permutations is low, and
less than `control$minperm`

, it is better to enumerate all
possible permutations, and as such complete enumeration of all
permutations is turned on (`control$complete`

is set to
`TRUE`

). This guarantees that permutations are all unique and
there are no duplicates.

For `check`

a list containing the maximum number of
permutations possible and an object of class `"how"`

.

Gavin L. Simpson

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | ```
## only run this example if vegan is available
if (suppressPackageStartupMessages(require("vegan"))) {
## use example data from ?pyrifos in package vegan
example(pyrifos)
## Demonstrate the maximum number of permutations for the pyrifos data
## under a series of permutation schemes
## no restrictions - lots of perms
CONTROL <- how(within = Within(type = "free"))
(check1 <- check(pyrifos, CONTROL))
## summary(check1)
## no strata but data are series with no mirroring, so 132 permutations
CONTROL <- how(within = Within(type = "series", mirror = FALSE))
check(pyrifos, CONTROL)
## no strata but data are series with mirroring, so 264 permutations
CONTROL <- how(within = Within(type = "series", mirror = TRUE))
check(pyrifos, control = CONTROL)
## unrestricted within strata
check(pyrifos, control = how(plots = Plots(strata = ditch),
within = Within(type = "free")))
## time series within strata, no mirroring
check(pyrifos,
control = how(plots = Plots(strata = ditch),
within = Within(type = "series", mirror = FALSE)))
## time series within strata, with mirroring
check(pyrifos,
control = how(plots = Plots(strata = ditch),
within = Within(type = "series", mirror = TRUE)))
## time series within strata, no mirroring, same permutation
## within strata
check(pyrifos,
control = how(plots = Plots(strata = ditch),
within = Within(type = "series", constant = TRUE)))
## time series within strata, with mirroring, same permutation
## within strata
check(pyrifos,
control = how(plots = Plots(strata = ditch),
within = Within(type = "series", mirror = TRUE,
constant = TRUE)))
## permute strata
check(pyrifos, how(plots = Plots(strata = ditch, type = "free"),
within = Within(type = "none")))
}
## this should also also for arbitrary vectors
vec1 <- check(1:100)
vec2 <- check(1:100, how())
all.equal(vec1, vec2)
vec3 <- check(1:100, how(within = Within(type = "series")))
all.equal(100, vec3$n)
vec4 <- check(1:100, how(within = Within(type= "series", mirror = TRUE)))
all.equal(vec4$n, 200)
## enumerate all possible permutations
fac <- gl(2,6)
ctrl <- how(plots = Plots(strata = fac),
within = Within(type = "grid", mirror = FALSE,
constant = TRUE, nrow = 3, ncol = 2))
check(1:12, ctrl)
numPerms(1:12, control = ctrl)
(tmp <- allPerms(12, control = update(ctrl, observed = TRUE)))
(tmp2 <- allPerms(12, control = ctrl))
## turn on mirroring
ctrl <- update(ctrl, within = update(getWithin(ctrl), mirror = TRUE))
numPerms(1:12, control = ctrl)
(tmp3 <- allPerms(12, control = update(ctrl, observed = TRUE)))
(tmp4 <- allPerms(12, control = ctrl))
## prints out details of the permutation scheme as
## well as the matrix of permutations
summary(tmp)
summary(tmp2)
## different numbers of observations per level of strata
fac <- factor(rep(1:3, times = c(3,2,2)))
## free permutations in levels of strata
numPerms(7, how(within = Within(type = "free"),
plots = Plots(strata = fac, type = "none")))
allPerms(7, how(within = Within(type = "free"),
plots = Plots(strata = fac)))
## series permutations in levels of strata
ctrl <- how(within = Within(type = "series"), plots = Plots(strata = fac))
numPerms(7, control = ctrl)
allPerms(7, control = ctrl)
``` |

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.