Re: sprintf to make filenames

[Mike Miller]

My question:

> I want to be able to use the usual save command of this form:
>
> save -ascii file_0001.dat matrixdata
>
> but I'd like for the filename to be determined by a variable in this
> sort of way:
>
> i=1;
> save -ascii sprintf("file_%04d.dat",i) matrixdata
>
> That doesn't work because Octave doesn't seem to interpret the sprintf
> command to produce the string for the filename.  How can I get this to
> work?


Below are all the answers I received.  They were extremely helpful.  I
would say that this solution will work best for me...

save("-ascii",sprintf("file_%04d.dat",i),"matrixdata")

...but the other stuff also helped a lot.  The help-octave list is still
going strong!  (I was last on it 2 years ago.)  Thanks very much.

Mike


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Use eval() and build the complete command string inside it. There are dozens
of examples in the list archives.


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either
        eval(sprintf("save -ascii file_%04d.dat matrixdata", i))
or
        save("-ascii",sprintf("file_%04d.dat",i),"matrixdata")


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Try :

  save ("-ascii",,sprintf("file_%04d.dat",i), "matrixdata")

Octave commands usually can be called as functions too.


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Use the "eval() function", Mike,

eval(['save -ascii ', sprintf("file_%04d.dat",i),' matrixdata']);


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That does work.  Here is an example:  "runNo" and "data_to_save"  are
defined by your code.

fnam_t= sprintf("%s.type",runNo);

str = sprintf("save %s  data_to_save",fnam_t);

eval(str);

Hope that helps.


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You can also use the functional version of save:

a=rand(1,5);
fname="foo.mat"
save("-ascii",fname,"a");

saves the variable "a" to the file "foo.mat" as ascii.


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Just to state what may be obvious:
I didn't use sprintf in the example. You can use sprintf to set
the variable "fname" to whatever you want.



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