Picking random points...

2015 11 5
1 个回答
回答已采纳
更新时间：2015 11 5
11 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 Logical 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