read few lines from one .m file and jump to another .m file

Question

Megha 2018-4-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/395192-read-few-lines-from-one-m-file-and-jump-to-another-m-file

评论： Megha 2018-4-18

Is it possible to read only few lines from one matlab code and then jump to another matlab code and read there another few set of lines and so on?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jan 2018-4-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/395192-read-few-lines-from-one-m-file-and-jump-to-another-m-file#answer_315356

This is not the purpose of program code. If you need only some lines of a specific function, create a copy of this functions and remove the other lines. Fortunately there are no magic GOTO or COMEFROM commands in Matlab. Reading the files by fileread and evaluating some lines by eval is a very bad idea also, because you would create a Meta-Matlab-Interpreter, which is too indirect and prone to bugs to be used efficiently.

6 个评论
显示 4更早的评论隐藏 4更早的评论

Jan 2018-4-17

编辑：Jan 2018-4-17

在 MATLAB Online 中打开

@Megha: You can select a block of code in the editor and run it specifically. But therefore the required variables must be existing before already, so this is rarely useful.

I do not understand, why running a few lines of code helps to deal with large data sets. "Loading all files" and "running all codes" sounds like two different jobs - except if the code consists of a list of load commands. But even then it sounds very easy to modify the script or function by editing it. E.g. a block comment or a if 0 ... end should be useful. Or maybe a control like:

function Data = YourCode(WhatToLoad)
switch WhatToLoad
  case 'all'
    Data{1} = load('asd.mat');
    Data{2} = load('other.mat');
  case 'firstOnly'
    Data{1} = load('asd.mat');
end

You see, no magic meta-commands required. if else or switch case are enough to control what is executed.

@Stephen: I have implemented PLEASE as mex function. It evaluates the provided function handle and arguments, but strings also. So it is a polite version of feval and eval. I do not publish it in the FileExchange to avoid being reminded to read Tutorial: Why to avoid EVAL.

DOWHATIWANTANDNOTWHATIWROTE is implemented as feature('dwim') already.

Stephen23 2018-4-18

编辑：Stephen23 2018-4-18

@Megha: no, there is not easy way to do that. It would be possible using some highly inefficient, slow, and likely buggy file reading and evaluation, but that would be an incredibly bad way to run code, and I would not recommend doing that. That is why Jan has also been advising you to use standard control statements, e.g. if or switch. Standard control statements are simple, efficient, and easy to debug. In fact that is exactly what control statements are for: for controlling which code runs. You should use them.

You should avoid doing the kind of magic that you are trying to do.

Megha 2018-4-18