隨機m×n矩陣的randperm子集

Question

如何使用randperm選擇數據的m乘n矩陣並輸出該隨機數據的較小子集？

即

newfile = randperm(data(m = 2000, n = 3)); %% save random m-by-n data as newfile 

Answer 1

考慮這個例子：

data = rand(8,6); 
m = 4; 
n = 2; 

%# pick random rows 
indX = randperm(size(data,1)); 
indX = indX(1:m); 

%# pick random columns 
indY = randperm(size(data,2)); 
indY = indY(1:n); 

%# filter data 
data2 = data(indX,indY) 

注意R2011b介紹了一個更簡單的語法RANDPERM，讓你直接寫：

indX = randperm(size(data,1), m); 
indY = randperm(size(data,2), n);