matlab随机样本的选择,matlab随机抽样 | 学步园

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 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.