need help with warning

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Neesha
Neesha on 5 Nov 2013
Commented: Image Analyst on 22 Dec 2015
I am trying to do following which gives me warning and code does not execute any further. Please help resolve this
A = [91, 89, 90, 93, 95, 97]
A.switch1 = A <=91;
A.switch2 = A > 91,
I get following warning. How do i make it right? THanks
============================= Warning: Struct field assignment overwrites a value with class "double". See MATLAB R14SP2 Release Notes, Assigning Nonstructure Variables As Structures Displays Warning, for details.

Accepted Answer

Image Analyst
Image Analyst on 5 Nov 2013
First you create a normal, typical numerical array of doubles. Then you create a structure with the same name, A. It's a structure because you added members/fields switch1 and switch2. I think it's just warning you that you're totally blowing away a variable with a completely new and different type of variable. Is that what you want to do? If it is, then just ignore the warning.
  2 Comments
Stephen23
Stephen23 on 22 Dec 2015
The OP is clearly confused, yet this answer does not really resolve the problem. Although the warning may be ignored on the second line, by the time the third line is run it will generate an error because the relational operator gt is not defined for structures. Ignoring the warning does not resolve this problem. A better solution would be to simply define a new variable for the structure, with a different name.
Image Analyst
Image Analyst on 22 Dec 2015
Some correction options:
% Possible fix #1.
dblA = [91, 89, 90, 93, 95, 97]
A.switch1 = dblA <= 91;
A.switch2 = dblA > 91,
% Possible fix #2.
A = [91, 89, 90, 93, 95, 97]
switch1 = A <= 91;
switch2 = A > 91;

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More Answers (2)

Neesha
Neesha on 5 Nov 2013
Well, i can ignore the warning but when my code comes to that line it stops executing. For now, I have gotten around creating dataset instead of struct. A = [91, 89, 90, 93, 95, 97] switch1 = A <=91; switch2 = A > 91,
I was using some legacy code which is using struct. I do not know if later stage if it helps it to be struct vs. dataset.
Thanks
  1 Comment
Image Analyst
Image Analyst on 5 Nov 2013
Warnings do not stop code, only errors do. Please accept my answer if you have no more questions. Thanks.

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Neil Caithness
Neil Caithness on 2 Feb 2015
From the latest release notes:
Assigning Structures to Nonstructures
Because of a bug, previous releases of MATLAB have allowed structure assignment to a nonempty nonstructure to overwrite the previous value. MATLAB continues to allow this in this release, but generates a warning message. In a future release, attempting this type of assignment will generate an error.
  2 Comments
Image Analyst
Image Analyst on 2 Feb 2015
Are you talking about the 2015a prerelease? Because this code generates no warning in R2014b:
% Create a non-empty variable "a" that is not a structure.
a=10;
% Create a structure, str.
str.field1 = 20;
str.field2 = 'abc';
% Now assign structure str to nonempty, nonstructure "a"
a = str; % No warning message.
Matthias Goldgruber
Matthias Goldgruber on 22 Dec 2015
You dont get a warning because you do something different!
Try the following:
a=10;
a.b=11;
Then you should get the same warning.

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