Picking random points...

2015 11 5
1 个回答
回答已采纳
更新时间：2015 11 5
17 次查看（30 天）

0 个投票

Hi
I am exploring a closed (time) interval between 0 and 1. I have used the linspace command to generate it:
t=linspace(0,1);
I can't seem to figure out how to randomly pick 10 (say) of these points in t so that I can plug them into a function (selected in a non-uniform way). Any thought?
Many thanks
Joe

请先登录，再回答此问题。

 采纳的回答

Stephen23
Stephen23 2015-11-5
编辑：Stephen23 2015-11-5

0 个投票

You can simply generate some indices to pick value from the vector t. I have shown you uniformly distributed random indices, because you did not tell us what random distribution you want. Two solutions are shown below: without and with index repetition.
t = linspace(0,1);
N = 5; % how many points to pick
Without repetitions use randperm:
>> idx = randperm(numel(t),N)
idx =
45 75 58 51 15
>> t(idx)
ans =
0.44444 0.74747 0.57576 0.50505 0.14141
With repetitions use randi:
>> idy = randi(numel(t),1,N)
idy =
53 44 11 77 71
>> t(idy)
ans =
0.52525 0.43434 0.10101 0.76768 0.70707

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Joe Bannen
Joe Bannen 2015-11-5
Stephen
Thanks for this. I am looking for an interval with non uniform nodes to use in my equation. How would this change things?
Cheers
Joe
Stephen23
Stephen23 2015-11-5
编辑：Stephen23 2015-11-5
Define your interval and distribution, and use these to generate some indices, exactly as I have shown.
Do you know which distribution you need?
Joe Bannen
Joe Bannen 2015-11-5
Stephen
I think you were correct in the first answer, it is my lack of understanding that is causing the problem.
I had been using:
t_1=rand(10,1);
But now need to randomly pick 10 items from:
t=linspace(0,1);
Since randn uses the standard normal distribution, your suggestion should work! Please let me know if I am wrong on this.
Best wishes
Joe
Thorsten
Thorsten 2015-11-5
Maybe you want to sort the 10 randomly picked numbers:
t=linspace(0,1);
t10 = t(sort(randperm(numel(t), 10)))

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

产品

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by