Variable names in loop?

Hey, I am trying to extract some environmental parameter measurements from netcdf format file and importing them to an excel file. Here is my code:

fullname={'india-20140101-ssrd-run00.nc'};

Varname='var169';

vardata=ncread(fullname,Varname);

i=1;
while i<26

sheet=i;
filename='india-20140101-ssrd-run00.xlsx';

   xlRange='B4:IH244';
   xlswrite(

    filename,vardata(:,:,i),sheet,xlRange);

    i=i+1;

    end;

I have to read data from several files with names:

india-20140102-ssrd-run00.nc india-20140103-ssrd-run00.nc india-20140104-ssrd-run00.nc india-20140105-ssrd-run00.nc . . .

Is it possible to employ a loop here?

Answer 1

[Chad Greene]

There are a couple of ways you can do this. One way is to populate a list of names manually before starting the loop:

filenames = {'my file 1'; 'my other file'; 'somebody else''s file'}; 

for k = 1:length(filenames) 
    disp(filenames{k}) 
end

Or if you're only incrementing numbers you can do it like this:

for k = 10:13 
    fullname = ['myfilenumber_',num2str(k),'.nc']; 
    disp(fullname)
end

[sujit]

Thank you Chad..

[Stephen23]

Using sprintf is quite a bit faster than concatenating strings:

N = 1e5;
tic
for k = 1:N
    ['myfilenumber_',num2str(k),'.nc'];
end
toc

tic
for k = 1:N
    sprintf('myfilenumber_%i.nc',k);
end
toc

Elapsed time is 5.014318 seconds.
Elapsed time is 0.923741 seconds.

It is a good habit to learn to use sprintf rather than string concatenation!

[Chad Greene]

That's awesome, Stephen!

[sujit]

Thank you Stephen..

Answer 2

[Brendan Hamm]

Sure there are multiple ways to do this.

1. Assuming all of the files are in the same directory (I assume the working) we can use the command:

fileList = dir('india-*'); % Returns a struct with info on the files that begin with 'india-'
fileNames = {fileList.name}; % Extract the file names into a cell array; 
for k = 1:length(fileNames)
    xlsread(fileNames{k},...); % Fill in the rest here
    % Perform more operations here
end

2. You could just start the loop at 20140101 and use strcat. I would use the first method, so will not elaborate here.