what does it mean by writing [~,idx] in code?

193 次查看（过去 30 天）

显示更早的评论

Sanuj Shukla 2013-4-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73735-what-does-it-mean-by-writing-idx-in-code

评论： Adam Danz 2023-3-14

采纳的回答： James Tursa

for p= 4:4:population

dists= total_dist(rand_pair(p-3:p));

[~,idx]=min(dists);

best = routes(idx,:);

what idx, ~ means??

5 个评论
显示 3更早的评论隐藏 3更早的评论

merlin toche 2023-3-13

@Steven Lord

please I posted the question as you asked so well but no answer. I went through this page because for 2 months my concerns have been ignored, can you explain this to me? thank you

merlin toche 2023-3-13

i have this error when i plot my code

attached

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

James Tursa 2013-4-27

15
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73735-what-does-it-mean-by-writing-idx-in-code#answer_83637

编辑：James Tursa 2013-4-27

在 MATLAB Online 中打开

The ~ represents an output that is discarded. It is essentially equivalent to:

[dummy,idx]=min(dists);
clear dummy

For this example, the code wants to work with the index of the minimum value, not the value itself, so the minimum value that is returned is discarded and only the index is retained.

http://www.mathworks.com/help/matlab/matlab_prog/ignore-function-outputs.html?searchHighlight=tilde

更多回答（1 个）

the cyclist 2013-4-27

9
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73735-what-does-it-mean-by-writing-idx-in-code#answer_83639

编辑：the cyclist 2013-4-27

在 MATLAB Online 中打开

When you see

>> [a,b,c] = function(...)

then a,b, and c are the output of a function. If you do not want one of the outputs of a function, then you can replace it with the ~ symbol:

>> [a,~,c] = function(...)

and then b will not be output.

To clarify, the syntax doesn't actually prevent the function from producing the output ... it just causes MATLAB to ignore the output and automatically clear it instead of assigning it to a workspace variable. So using the syntax makes your code cleaner looking but the function will still use the same resources (time & memory) to run.

请先登录，再进行评论。

请先登录，再回答此问题。