How can I remove a variable from the parent workspace while a function is using it?

2 次查看（过去 30 天）
Sean
Sean 2011-12-14
I work with fairly large datasets, so the fact that they get duplicated when a function accepts them as an input can be a problem given 32bit memory constraints.
I have started using scripts instead of functions in order to save on memory usage, but this has caused additional problems, because now their is no distinction between the workspaces and I have to be very careful not to overwrite utility variables (such as x, y, t, n, etc.)
I would really like to pass a variable as a function input such that there are not two copies floating around the system.
How can I remove the variable from the parent workspace (or possibly act directly on only the parent workspace variables that are specified as functional inputs?)
Thanks, Sean

请先登录，再回答此问题。

采纳的回答

the cyclist
the cyclist 2011-12-14
Are you changing the value of the variable after it is passed in? If not, then a copy is never made.
If it is changed, you could define the variable as global to ensure having only one copy.
  3 个评论
显示 1更早的评论
Sean
Sean 2011-12-14
I have a natural aversion to using global variables, because it is so easy to cause problems that way, but perhaps this is one of the few 'correct' times to use a global...
The reason I am not using nested functions is because I do not want to risk overwriting other variables in the parent workspace.
Walter Roberson
Walter Roberson 2011-12-14
The only variables that can be overwritten are the ones that are initialized before the nested routines are declared.
function parent
shared1=[];
function nested1
shared1='hello'; %affects shared variable
i=15; %local variable because it was not initialized before nested routine
end
i=32; %local variable because it was not initialized before nested routine
nested1(); %will affect shared1 but not i
end

请先登录，再进行评论。

更多回答（1 个）

Walter Roberson
Walter Roberson 2011-12-14
To answer the original question:
evalin('caller', ['clear ', inputname(3)])
where the 3 here should be changed to the parameter number of the variable in the calling sequence.
Crashes due to doing this would not surprise me.
  1 个评论
Sean
Sean 2011-12-14
Walter,
Thanks for the answer. I was unfamiliar with the 'evalin' command. I can see that it would work for what I was asking, but can also potentially be badly abused. :)
I would mark you as the accepted answer, but I already marked 'the cyclist' as such.
Thanks again,
Sean

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Workspace Variables and MAT-Files 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by