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MathGroup Archive 2005

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Re: importing mat format doesn't import variable names

  • To: mathgroup at smc.vnet.net
  • Subject: [mg53511] Re: importing mat format doesn't import variable names
  • From: Ben Barrowes <barrowes at alum.mit.edu>
  • Date: Sat, 15 Jan 2005 01:44:10 -0500 (EST)
  • References: <200501130812.DAA03781@smc.vnet.net> <cs8kid$ejl$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

It seems that Import extracts only numerical data and loses the variable 
names from MAT files.

OK, how about an Export problem?

Let's say I have two arrays:
aa={2,3}
and
bb={{9,8,7},{6,5,4},{3,2,1}}

How can I save both of these to a MAT file?

I can save either one, e.g.:
Export["filename",aa,"MAT"];

But if I try to:
Export["filename",{aa,bb},"MAT"];

The resulting file size is 0 and the Import consequently fails.

Any way to export more than one matrix to a MAT file?


What I would really like to do is save all the currently defined 
variables to a MAT file. I tried:

Export["filename",ToExpression[Names["`*"]],"MAT"];

But that fails in the same way as the preceeding example when there is 
more than one variable defined.



Tomas Garza wrote:
> Could you give us a small example of the file you're trying to import 
> (perhaps 3 x 3), including the variable names?
> 
> Tomas Garza
> Mexico City
> ----- Original Message ----- 
> From: "Ben Barrowes" <barrowes at alum.mit.edu>
To: mathgroup at smc.vnet.net
> Subject: [mg53511]  importing mat format doesn't import variable names
> 
> 
> 
>>This is a very responsive ng. Thanks!
>>
>>When I Import["file","MAT"] files, the variable name information is
>>lost. Is this the normal behavior? Or is there a switch I can specify to
>>import the variable names as well?
>>
>>For example, if file.mat has two variables, foo (3x3) and bar (3x3), and
>>I Import it, all I get is 1 nested List for a result.
>>{{{foo[[1,1]],foo[[1,2]],foo[[1,3]]},...},{{bar[[1,1]],...}}}
>>However, they are simply numbers with no names associated with the list.
>>
>>I know I could do:
>>{foo,bar}=Import["file.mat","MAT"];
>>
>>but I was wondering if there was a way to Import variable names without
>>specifying them explicitly. The information is in the .mat file. Why
>>doesn't Mathematica extract it?
>>
>>Similarly, when I Export a matrix into a mat file, will the variable
>>name be lost?
>>
>>Ben Barrowes
>>
>>
> 
> 
> 


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