Why the regexp returns wrong result?

Hi,

I use who function and '-regexp' to help me sort data that matches my criteria.

dataList = who(subBatchData,'-regexp','^X.*2');

It works well in other data. While in this data, it returns wrong result. And in the same batch, using '^X.*4'/ '^X.*8' can also get correct results.

So, why it returns wrong answer?

[Stephen23]

Having lots of numbered variable names is usually a sign that something is going wrong:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

The MATLAB documentation states "Avoid functions that query the state of MATLAB such as inputname, which, whos, exist(var), and dbstack. Run-time introspection is computationally expensive."

source: https://www.mathworks.com/help/matlab/matlab_prog/techniques-for-improving-performance.html

The most important question is: how did you get all of those variables into the workspace? There is probably a more robust and more efficient approach to processing this data.

Answer 1

[Askic V]

Because you have a match, for example, for the first element:

X2300IF_S1

Did you perhaps want:

'^X.*2$'

so that 2 must be at the end?

[Wei Sue]

Thank you for your answer!

I didn't realize that I forgot the `$` in the expression.

Thanks for your time again.

[Askic V]

If you are satisfied with the answer, please accept the reply as an answer to your question. Thank you.