matlab隨機抽樣

1。程式實現

設資料存放於向量a中，需要重複n次簡單隨機採樣，程式及說明如下：
m=length(a); %dimension
idx= ceil(m*rand(1,n)) ; %generate n random index between 1 and m
b = a(idx) ; % sampling

 

2。內建函數

RANDSAMPLE Random sample, with or without replacement.
Y = RANDSAMPLE(N,K) returns Y as a vector of K values sampled
uniformly at random, without replacement, from the integers 1:N.

Y = RANDSAMPLE(POPULATION,K), where POPULATION is a vector of two or more
values, returns K values sampled uniformly at random, without replacement,
from the values in the vector POPULATION.

Y = RANDSAMPLE(...,REPLACE) returns a sample taken with replacement if
REPLACE is true, or without replacement if REPLACE is false (the default).

Y = RANDSAMPLE(...,true,W) returns a weighted sample, using positive
weights W, taken with replacement. W is often a vector of probabilities.
This function does not support weighted sampling without replacement.

Y = RANDSAMPLE(S, ...) uses the random stream S for random number
generation. S is a random stream created using RandStream.
Default is the MATLAB default random number stream.

Example: Generate a random sequence of the characters ACGT, with
replacement, according to specified probabilities.

R = randsample('ACGT',48,true,[0.15 0.35 0.35 0.15])

See also rand, randperm, RandStream.