How do I loop this code to open each file, conduct a simple operation and resave?

Hi,

I have a bunch .csv with five columns. I am trying to create a loop that will open each file in the directory, take each value in column 5 and add one to it and place it in a new column (column 6) and overwrite the previous file (but not delete the existing values)

I have the following code, but how do I open each one sequentially?

%Matlab code to create matrix for files

Files = dir('c:\Users\Laurentiu Galan\Desktop\tickoutput\*.csv');
fnames = {Files.name};
filename = fnames';

%Determine Size for Loop
D = size(filename);
Numloop = D(1,1);

%Loop to Create Paths for each file
for i=1:Numloop
    thispath(i,1) = strcat('c:\Users\Laurentiu   
    Galan\Desktop\tickoutput\', filename(i,1));
    end  

%Loop to open each file and add one to each value in a new column 'column 6'????
???

Thanks, I know its a nested if then statement, any ideas?

Answer 1

[Fangjun Jiang]

Start with this and then do the data processing.

PathStr('c:\Users\Laurentiu Galan\Desktop\tickoutput');
Files = dir(fullfile(PathStr,'*.csv'));

for k=1:length(Files)
    Data=importdata(fullfile(PathStr,Files(k).name));
end

[Laurentiu Galan]

I got. this way gave me an error. I used

%%

PathStr = 'c:\Users\Laurentiu Galan\Desktop\tickoutput';

Files = dir(fullfile(PathStr,'*.csv'))

%%

%for k=1:length(Files)

% Data=importdata(fullfile(PathStr,Files(k).name));

%end

and it worked.

I've never used directories before. I'm going to have 23,000 files in this directory. Matlab will crash. I will need to open each file individually for it to work

[Laurentiu Galan]

Any ideas how not to do it with the directory?

[Walter Roberson]

You cannot do it without using dir()

Your code shown does not read in any data, and so is not functional as is.

MATLAB will not inherently crash for importing 23000 files.

Answer 2

[Image Analyst]

Very simple. Use csvread() to read it into an array, insert your new column, use csvwrite() to write out the new array. Follow the examples in the FAQ for reading and writing a bunch of files in a loop:

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F