matlab向量的简单随机抽样,matlab随机抽样

1。程序实现

设数据存放于向量a中，需要重复n次简单随机采样，程序及说明如下：

m=length(a); %dimension

idx= ceil(m*rand(1,n)) ; %generate n random index between 1 and m

b = a(idx) ; % sampling

2。自带函数

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 morevalues, 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 ifREPLACE is true, or without replacement if REPLACE is false (the default).Y = RANDSAMPLE(...,true,W) returns a weighted sample, using positiveweights 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, withreplacement, according to specified probabilities.R = randsample('ACGT',48,true,[0.15 0.35 0.35 0.15])See also rand, randperm, RandStream.