How to save a structure as .mat?

I am trying to save a 1x6 structure named 'PIN' as a .mat file. When I attempt to use save(newfilename.mat,'PIN'), I get this error: Attempt to reference field of non-structure array.

How would I go about saving this structure as a .mat file with the specified name?

[Stephen Cobeldick]

Original question by Ibro Tutic on 4th November 2015 retrieved from Google Cache:

http://web.archive.org/web/20201226074447/https://webcache.googleusercontent.com/search?q=cache%3AHLPDZvl-VcQJ%3Ahttps%3A%2F%2Fes.mathworks.com%2Fmatlabcentral%2Fanswers%2F252884-how-to-save-a-structure-as-mat

How to save a structure as .mat?

I am trying to save a 1x6 structure named 'PIN' as a .mat file. When I attempt to use save(newfilename.mat,'PIN'), I get this error: Attempt to reference field of non-structure array.

How would I go about saving this structure as a .mat file with the specified name?

 projectdir = 'C:\Users\it58528\Documents\Dig Test';    %Start here. or name an absolute directory
 newdir = 'C:\Users\it58528\Desktop\Test';
 folderinfo = dir(projectdir);
 folderinfo = folderinfo([folderinfo.isdir]);  %select only the directories
 folderinfo = folderinfo(~ismember({folderinfo.name}, {'.', '..'}));  %remove directories . and ..
 %%%%%%%%%%%%%%%%%Digs for Files/Reads/Saves %%%%%%%%%%%%%%%%%%%%%
 for folderidx = 1 : length(folderinfo)
  thisfolder = fullfile(projectdir, folderinfo(folderidx).name);
  subfolderinfo = dir(thisfolder);
  subfolderinfo = subfolderinfo([subfolderinfo.isdir]);  %select only the directories
  subfolderinfo = subfolderinfo(~ismember({subfolderinfo.name}, {'.', '..'}));   %remove directories . and ..
  folderidxi = folderinfo(folderidx).name;
  newfolder = fullfile(newdir, folderidxi);
  mkdir(newfolder);
for subfolderidx = 1 : length(subfolderinfo)
 subfolderi  = subfolderinfo(subfolderidx).name;
 thissubfolder = fullfile(thisfolder, subfolderi);
 fileinfo = dir( fullfile(thissubfolder, '*.csv') );
   newsubfolder = fullfile(newfolder, subfolderi);
   mkdir(newsubfolder);
    for fileidx = 1 : length(fileinfo)
        filenamei = fileinfo(fileidx).name;
        thisfile = fullfile(thissubfolder, filenamei);
        [filepath, basename, ext] = fileparts(thisfile);
        data = csvread(thisfile,5,2);
        PIN(fileidx).PIN = fileinfo(fileidx).name(1:17);
        %FIX THIS PIN(fileidx).serialnumber = data(1,2); //serial number 
        PIN(fileidx).loadprofile = data(1:15,:);
        PIN(fileidx).hours = sum(sum(PIN(fileidx).loadprofile,1));
        PIN(fileidx).loadprofilepercent = PIN(fileidx).loadprofile./PIN(fileidx).hours;
        PIN(fileidx).loadpercent = data(:,2);
        PIN(fileidx).RPM = data(16,:);
        loadprofilecolumn = find(PIN(fileidx).RPM>Resonance);
        xSpeed = PIN(fileidx).RPM(loadprofilecolumn(1)-1);
        newfilename = fullfile(newsubfolder, filenamei);
        save(newfilename.mat,'PIN'); %%%%FIX
    end   %files within subfolder
   end     %subfolders within folder
 end       %folders

Answer 1

[Kirby Fears]

newfilename is a variable in your workspace when you define it as

newfilename = fullfile(newsubfolder, filenamei);

In your first argument to save(), you say "newfilename.mat", which attempts to access the mat field of object newfilename. Hence the error Attempt to reference field of non-structure array.

Try this syntax instead:

save(newfilename,'PIN');

Or if you really want to tag ".mat" on the end explicitly:

save([newfilename,'.mat'],'PIN');

[Ibro Tutic]

I tried that initially and it doesn't save the structure 'PIN'. It just takes the original .csv file that I am reading and saves it to a new directory. What I need it to do is save the PIN structure as a .mat file with the same name as the original file.

I think the issue lies in the filename somewhere, I feel like my program might be considering .csv a part of the file name and when it saves, it is automatically considered a .csv file? To add on to this, this looks like the issue. newfilename is saved as 'theoriginalfilename'.csv. What I need to do is just take 'theoriginalfilename' and leave off the .csv, any ideas on how to go about this?

When I tried tag .mat on at the end explicitly, the file was saved as 'the original file name'.csv.mat.

When I use the command window and type save('PIN','PIN'), it does what I want it to do, but it saves the file in the location of the matlab program. It's fairly useless to me since I have to do this to thousands of files and typing save('PIN','PIN') every time would be idiotic.

[Ibro Tutic]

I figured it out, thanks.