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Topic: trouble saving data structure to a file
Replies: 7   Last Post: Nov 12, 2012 10:21 AM

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Ben Ruppel

Posts: 25
Registered: 3/17/11
Re: trouble saving data structure to a file
Posted: Nov 8, 2012 5:35 PM
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"Steven_Lord" <slord@mathworks.com> wrote in message <k7b9r0$ahr$1@newscl01ah.mathworks.com>...
>
>
> "Ben Ruppel" <brspam@cox.net> wrote in message
> news:k7b6ao$q01$1@newscl01ah.mathworks.com...

> > "Steven_Lord" <slord@mathworks.com> wrote in message
> > <k7a66a$asf$1@newscl01ah.mathworks.com>...

>
> *snip*
>

> > Thank you very much, your solution worked. I'm not thrilled with creating
> > a copy of A, B, and C since these are very large variables.

>
> Depending on what you're doing, you may not be creating an actual copy.
>
> http://www.mathworks.com/help/matlab/matlab_prog/memory-allocation.html
>
> The copy-on-write behavior may save you from actually making a copy.
>

> > How can you tell that handles.inputData is not a scalar struct variable?
>
> Variable names in MATLAB have four specific rules:
>
> http://www.mathworks.com/help/matlab/ref/isvarname.html
>
> 'handles.inputData' contains a period, which is not allowed in variable
> names. That makes it an expression that when evaluated returns a variable.
> If you assign the output of that expression to an identifier, that
> identifier must be a valid variable name.
>

> > In Variable Editor both handles and handles.inputData are listed as "1x1
> > struct". Furthermore, they are both data "things" in matlab which contain
> > multiple data structures and arrays and cell arrays. What makes the one
> > different from the other?

>
> "Ben Ruppel" is the name you use to post to CSSM.
>
> "The person that posts to CSSM using the address 'brspam@cox.net' " refers
> to you, but it is not your name. If I "evaluate" that expression by
> searching CSSM, I can find your actual name. [Not the best of examples, as
> anyone can spoof their email address, but hopefully good enough for
> illustration purposes.]
>

> > Is there a way for me to make handles.inputData a scalar struct variable?
>
> For purposes of SAVE? Not without assigning it to a variable.
>

> > Or is the problem more that handles.inputData is an expression? If that
> > is the case, is there a way to point to this data structure that does not
> > count as an expression?

>
> If you're worried about memory, see above.
>
> --
> Steve Lord
> slord@mathworks.com
> To contact Technical Support use the Contact Us link on
> http://www.mathworks.com


Hi Steve,
Thank you for the information and the useful links. While I accept it as the truth, I still think it's a little odd and inconsistent that some functions aren't smart enough to figure out when an expression points to a variable. After all, if I were to create my own function, I could pass in a variable name or a data structure member reference / expression and the function would see both as the data that is being referenced. Oh well.
-Ben



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