Using assignin in GUIDE

Question

Roy Veldhuizen 2012-6-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/41266-using-assignin-in-guide

评论： Neel Maharaj 2021-4-30

Hello everybody,

I've got a problem in which I want to generate variables of a structure I've got a structure called newData which consists of data, given by the matrix 'data' and the imported text in the cell called 'textdata'. I want to seperate the two variable in the structure. Before I used the following code

 newData = importdata(file, ' ', 6); %imports data 
% Create new variables in the base workspace from those fields. 
vars = fieldnames(newData); % which are 'data' and 'textdata' 
for i = 1:length(vars) 
%this should create the variables 'data' and 'texdata' 
assignin('base', vars{i}, newData.(vars{i})); 
end 
%which results in an error, as 'textdata' is not created by the assignin.
headers = char(textdata(6,:));

The error is generated by the fact that apparently, the variables data and textdata are not created (or not created in the right workspace) and consequently matlab cannot find these variables in further calculations (in this case the creation of headers cannot be executed, since 'textdata' is unknown.)

I used this piece before in a single m-file, and this worked perfect, But now I'm incorporating this in a GUI, so i need to use this within a function, which results in errors. I've also tried to write this piece in a different function m-file, which yields the same results. Basically, the problem is: how to use assignin within a (GUI) function, or perform the same action without using assignin?

I hope the problem is clear, and you guys can help me out.

Sincerely,

Roy

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Roy Veldhuizen 2012-6-18

Well my code looks like this

newData = importdata(file, ' ', 6); %imports data

% Create new variables in the base workspace from those fields.

vars = fieldnames(newData); % which are 'data' and 'textdata'

for i = 1:length(vars)

assignin('base', vars{i}, newData.(vars{i})); %which should create the variables 'data' and 'texdata'

end

headers = char(textdata(6,:)); %which results in an error, as the textdata variable is not created by assignin.

I've tried using the options that are listed under http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F but these only address the problem of passing the variable from one callback to another.

When I use the debugger, I do not see the variables being created and thus I think the issue generating the variables, rather than passing them from one callback to another..

Walter Roberson 2012-6-18

assignin('base') writes data into the base workspace, which is the workspace that is active when you are not inside any function (e.g., the workspace you get if you start assigning variables at the command line just after entering MATLAB.)

assignin('base') does NOT write variables into the current workspace (not unless the current workspace _is_ the base workspace, such as if you are executing a script from the command line.)

You write variables into the base workspace but then you try to use them in the current workspace.

headers = char(evalin('base', 'textdata(6,:)'));

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Answer 1

Walter Roberson 2012-6-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/41266-using-assignin-in-guide#answer_50870

Please consider the alternatives to using the base workspace: http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

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Neel Maharaj 2021-4-30

Love this! Stackoverflow Simulator: Matlab edition

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Answer 2

Roy Veldhuizen 2012-6-27

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/41266-using-assignin-in-guide#answer_51928

Based on documentation I decided that it was best not to use assignin, and used on of the methods specifically exporting to a mat file as given by Walter: http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F