如何产生与几率相关矩阵
matlab里有没这样的函数？或者可以编程实现以下功能，比如给出一个一维矩阵A，其值介于0－－100之间，把这个矩阵二值化为只有0和1两个值的矩阵B，方法为：假设A=;我想让生成的矩阵B中的元素个数与矩阵A中的元素个数同（size(A)=size(B)），当A(1)=97时，B(1)有97%的几率等于1，当A(2)=79时，B(2)有79%的几率等于1(即有21%的几率等于0)，以此类推。最后生成的B为1*10的一维矩阵，且只包含0和1两个数值。这个怎么实现？还望高手指点。[ 本帖最后由 ChaChing 于 2010-4-18 11:32 编辑 ] A=;
c=rand(1,10)*100;B=A>c
回复 沙发 yufeng 的帖子
请扫盲下rand出来的数字, 代表几率吗? 试试这个：
>> A = ;
>> R = mnrnd(1,);
>> B = R(:,1)'
B =
1 1 1 0 0 0 0 1 0 1
现在的版本较旧(无mnrnd函数), 尚无法验证学习!
但谢老师的, 个人有信心, 先加威望了
回复 5楼 ChaChing 的帖子
谢谢ChaChing大哥的信任和鼓励！回复 6楼 xiezhh 的帖子
你好，谢老师，如果我想生成一个100X100的0 1矩阵，其中只有100个1，就是说1的概率是0.1，怎么生成呢？回复 7楼 maigicku 的帖子
研究下这个就该差不多了吧mnrnd
Multinomial random numbers
Syntax
r = mnrnd(n,p)
R = mnrnd(n,p,m)
R = mnrnd(N,P)
Description
r = mnrnd(n,p) returns random values r from the multinomial distribution with parameters n and p. n is a positive integer specifying the number of trials (sample size) for each multinomial outcome. p is a 1-by-k vector of multinomial probabilities, where k is the number of multinomial bins or categories. p must sum to one. (If p does not sum to one, r consists entirely of NaN values.) r is a 1-by-k vector, containing counts for each of the k multinomial bins.
R = mnrnd(n,p,m) returns m random vectors from the multinomial distribution with parameters n and p. R is a m-by-k matrix, where k is the number of multinomial bins or categories. Each row of R corresponds to one multinomial outcome.
R = mnrnd(N,P) generates outcomes from different multinomial distributions. P is a m-by-k matrix, where k is the number of multinomial bins or categories and each of the m rows contains a different set of multinomial probabilities. Each row of P must sum to one. (If any row of P does not sum to one, the corresponding row of R consists entirely of NaN values.) N is a m-by-1 vector of positive integers or a single positive integer (replicated by mnrnd to a m-by-1 vector). R is a m-by-k matrix. Each row of R is generated using the corresponding rows of N and P.
Example
Generate 2 random vectors with the same probabilities:
n = 1e3;
p = ;
R = mnrnd(n,p,2)
R =
215 282 503
194 303 503
Generate 2 random vectors with different probabilities:
n = 1e3;
P = [0.2, 0.3, 0.5; ...
0.3, 0.4, 0.3;];
R = mnrnd(n,P)
R =
186 290 524
290 389 321
回复 8楼 dreamstone 的帖子
ls给的就是matlab的help嘛!? 已经解决了，用randperm
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