mosaic (version 0.2-3)

sample: Random Samples and Permutations

Description

These extensions to the base::sample make resampling and randomization tests easier.

Usage

sample(x, size, replace = FALSE, ...)
## S3 method for class 'matrix':
sample(x, size, replace = FALSE, prob = NULL, 
	groups = NULL, orig.ids = FALSE, ...)
## S3 method for class 'data.frame':
sample(x, size, replace = FALSE, prob = NULL, groups = NULL,
                 orig.ids = TRUE, fixed = names(x), shuffled = c(),
                 invisibly.return = NULL, ...)
## S3 method for class 'factor':
sample(x, size, replace = FALSE, prob = NULL, 
	groups = NULL, orig.ids = FALSE, drop.unused.levels=FALSE, ...)
## S3 method for class 'default':
sample(x, size, replace = FALSE, prob = NULL, groups = NULL, 
    orig.ids = FALSE, ...) 
resample (x, size, replace=TRUE, prob=NULL, groups=NULL, orig.ids=FALSE, ...) 
shuffle(x, replace = FALSE, prob = NULL, 
	groups = NULL, orig.ids = FALSE)
deal(x, size, replace = FALSE, prob = NULL, 
	groups = NULL, orig.ids = FALSE)
rflip(n=1, prob=.5, quiet=FALSE, verbose=!quiet)
nflip(n=1, prob=.5, ...)
## S3 method for class 'cointoss':
print(x,...)

Arguments

x

an object (typically a data frame, matrix, or vector)

size

size of the sample

n

number of coins to toss

replace

a logical indicating whether sampling is to be done with replacement.

prob

a vector of probability weights for obtaining the elements of the object being sampled, or the probability of heads for rflip and nflip.

groups

If present, shuffling is done within groups given by this vector. In this case size, if present, is ignored.

orig.ids

If TRUE and x is a data frame or a matrix, then the original locations of the data is recorded in the object returned.

quiet

If TRUE, suppress output.

verbose

If FALSE, suppress output.

drop.unused.levels

a logical. Remove unused levels from factors?

fixed

vector of columns that are not permuted

shuffled

vector of columns that are permuted

invisibly.return

a logical indicating whether result should be returned invisibly.

...

Additional arguments.

Value

• an object of the same type as x unless x is an integer, which case a vector is returned.

Examples

denominations <- c(2:10,c("J","Q","K","A"))
suits <- c("C","D","H","S")
cards <- as.vector(outer(denominations, suits, paste, sep="") )
shuffle(cards)
set.seed(52)
sample(cards, 13)
set.seed(52)
deal(cards, 13)      # same as sample(cards, 13)
resample(cards, 20)  # same as sample(..., replace=TRUE)
sample(cards, groups=rep(1:4, each=13))
rflip()              # flip 1 coin
rflip(20)            # flip 20 coins
nflip(20)            # flip 20 coins and only show the number of heads
table(do(1000) * nflip(20))   # a table based on flipping 20 coins 1000 times
table(do(1000) * nflip(20,.25))   # a table based on flipping 20 biased coins 1000 times