Sampling from large pools
bigsample samples quicker from large pools than sample does.
bigsample(x, ...) ## Default S3 method: bigsample(x, size, replace = FALSE, prob = NULL, negative = FALSE, ...) ## S3 method for class 'ff' bigsample(x, size, replace = FALSE, prob = NULL, ...)
x |
the pool to sample from |
size |
the number of elements to sample |
replace |
TRUE to use sampling with replacement |
prob |
optional vector of sampling probabilities (recyled to pool length) |
negative |
|
... |
|
For small pools sample is called.
a vector of elements sampled from the pool (argument 'x')
Note that bigsample and sample do not necessarily return the same sequence of elements when set.seed is set before.
Daniel Adler, Jens Oehlschlägel, Walter Zucchini
message("Specify pool size")
bigsample(1e8, 10)
message("Sample ff elements (same as x[bigsample(length(ff(1:100 / 10)), 10)])")
bigsample(ff(1:100 / 10), 10)
## Not run:
message("Speed factor")
(system.time(for(i in 1:10)sample(1e8, 10))[3]/10)
/ (system.time(for(i in 1:1000)bigsample(1e8, 10))[3]/1000)
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.