Use save append option in a for loop
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From: StarkEffekt Heiles on 18 May 2010 14:46 Hi MatlabCentral Members! For one of my research projects I have to deal with big matrices which are generated in a for loop. Since my memory is limited I have to clear my workspace before the next cycle of the loop can start. I asked myself if it is possible to save and append files with the same file name created in the loop? I tried save with the option append but the new data replaces the old file with the same name. Thanks in advance StarkEffekt
From: Walter Roberson on 18 May 2010 15:10 StarkEffekt Heiles wrote: > For one of my research projects I have to deal with big matrices which > are generated in a for loop. Since my memory is limited I have to clear > my workspace before the next cycle of the loop can start. I asked myself > if it is possible to save and append files with the same file name > created in the loop? I tried save with the option append but the new > data replaces the old file with the same name. The only case that I _know_ of where save -append gives unexpected results is if you are using binary files (the default) and the new variable you save has the same name as an existing variable in the file. If you do have this situation, then the entire .mat file will not be overwritten, but the new contents of the variable will replace the old contents of the variable.
From: Steven Lord on 18 May 2010 16:11
"Walter Roberson" <roberson(a)hushmail.com> wrote in message news:hsuoof$7c0$2(a)canopus.cc.umanitoba.ca... > StarkEffekt Heiles wrote: > >> For one of my research projects I have to deal with big matrices which >> are generated in a for loop. Since my memory is limited I have to clear >> my workspace before the next cycle of the loop can start. I asked myself >> if it is possible to save and append files with the same file name >> created in the loop? I tried save with the option append but the new data >> replaces the old file with the same name. > > The only case that I _know_ of where save -append gives unexpected results > is if you are using binary files (the default) and the new variable you > save has the same name as an existing variable in the file. If you do have > this situation, then the entire .mat file will not be overwritten, but the > new contents of the variable will replace the old contents of the > variable. Walter, the behavior you describe as "unexpected" is actually the documented behavior. Take a look in the description of "-append" in the Input Arguments section of the documentation for SAVE: http://www.mathworks.com/access/helpdesk/help/techdoc/ref/save.html?BB=1 In this case, '-append' means "add new variables to the file" not "add new content to the variables already in the file". If either of you (or anyone else) are interested in the latter meaning, I think that would make a perfectly reasonable enhancement request to file with Technical Support (along with your use case for how you'd use such a feature.) It would likely be tricky to determine what it should do when used with the -ascii flag, so if that scenario is important to you I suggest describing your expectations in your request. -- Steve Lord slord(a)mathworks.com comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ To contact Technical Support use the Contact Us link on http://www.mathworks.com |