Matlab is returning error "Argument must contain a string." when using "save"

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Thumree Sarkar
Thumree Sarkar 2018-12-27
编辑： Stephen23 2018-12-27
Hi,
I am trying to save some 3D variables in different named .mat files. I have created the filenames and variables in for loop. I am putting the files in cell (some cells wil be empty, I have some more for loops and if cnditions in between which I have not showed in the sample code) so that I can save them later. Matlab is giving me the error "Argument must contain a string.". I tried saving the files in the for loop previously but Matlab gave the same error.
I have tried running the code for a single year also, with the same error msg.
If the filenames are not variale then the save option is working fine, but I need to vary the filenames as they are representative of the year.
Please help me to save the variables.
path='somepath';
data=dir('somepath\*.TXT');
years={'2007';'2008';'2009';'2010';'2011';'2012';'2013';'2014';'2015';'2016'};
for i=1:size(data,1)
addpath(fullfile(path));
for j=1:size(years,1)
filenames=data(i).name;
filestring=cellstr(filenames);
xx=regexp(filestring,'\d','Match');
totreg=cellstr(xx{:});
pp=strcat(totreg(1),totreg(2),totreg(3),totreg(4));
year=str2double(pp);
if year == str2double(years(j));
filenames
'found the file'
if mod(str2double(years(j)), 4) == 0 && mod(str2double(years(j)), 100) ~= 0
'status = true2'
fileread2=dlmread(filenames,'',0,1);
Data_rain_leap2(:,:,:)=reshape(fileread2, [366,130,135]);
Data_rain_2{j}=Data_rain_leap2(:,2:end,:);
outputfilename2{j}=strcat('Data_',pp,'.mat');
addpath(fullfile(path));
%save(outputfilename2(j),'Data_rain_2'); it is also not working
else
'status = false'
fileread3=dlmread(filenames,'',0,1);
Data_rain_leap3(:,:,:)=reshape(fileread3, [365,130,135]);
Data_rain_3{j}=Data_rain_leap3(:,2:end,:);
outputfilename3{j}=strcat('IMD_grid_',pp,'.mat');
end
end
end
end
addpath(fullfile(path));
xx=find(~cellfun(@isempty,Data_rain_3));
Data_rain_3XX=Data_rain_3{xx};
save(outputfilename3{xx},'Data_rain_3XX');
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Thumree Sarkar
Thumree Sarkar 2018-12-27
Thanks for the suggestion.
I know the part with extracting the year in filename could be much simpler but when in practice was returning some error. I will use your suggested modification.
For the use of path, I have seen sometimes, if I do not redirect the path the code is not able to find the folders/write in the specific folders, (As I have too many data and too many folders). So I use that.
I will surely keep your suggestions in mind and try to make my codes more efficient and simpler in future.
Stephen23
Stephen23 2018-12-27
编辑：Stephen23 2018-12-27
" ...if I do not redirect the path the code is not able to find the folders/write in the specific folders"
All MATLAB functions that read/write data files accept absolute/relative filenames, so there is absolutely no need to change the Search Path (or to change the current directory) just to access data files. Using an absolute/relative filepath is more efficient and easier to debug too.

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madhan ravi
madhan ravi 2018-12-27
编辑：madhan ravi 2018-12-27
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Thumree Sarkar
Thumree Sarkar 2018-12-27
Thank you very much for the help. sprintf works fine and the problem with 'save' is also not there. Thanks a loottt.

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更多回答（1 个）

Walter Roberson
Walter Roberson 2018-12-27
save(outputfilename{xx},'Data{xx}');
You cannot use an expression for the name of the variable to save. You would need to do something like
Dataxx = Data{xx};
save(outputfilename{xx}, 'Dataxx');
If you did, then the name of the variable that got stored in the .mat file would be Dataxx . If you need the variable name to be dynamic, then there is a different approach that you would need to use.
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Thumree Sarkar
Thumree Sarkar 2018-12-27
No, actually ''pp'' is a string. Btw, my problem is solved now, I have accepted the answer by Mr Ravi, I think strcat was making some issue :(. Thanks for your time :)

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