reading data by column

Hello, I have data that is n x m (rows,column). I want to read each column and perform some analysis on the data prior to moving on to another column and performing the same analysis.

Is there a method on how to perform this reiterative process? Thanks,

Answer 1

[Voss]

If you have an n-by-m matrix you can do as follows:

n = 100;
m = 50;
data = randn(n,m);

results = cell(1,m);
for jj = 1:m
    results{jj} = perform_analysis(data(:,jj));
end

Where perform_analysis() is a function that performs the analysis you want to do on each column and returns something.

If instead your data is in a file, it may or may not be convenient to read it by column, depending on the file format.

[Arif Hoq]

hello @Benjamin. would you please light up about this error? is it matlab tool related error?

Unrecognized function or variable 'perform_analysis'.

Error in Untitled47 (line 9)
    results{jj} = perform_analysis(data(:,jj));

[Michael Angeles]

Thank you, I forgot to state that the data are in cells array.

[Voss]

@Arif Hoq: perform_analysis() is meant to be a stand-in for whatever analysis needs to be done on each column of data.

@Michael Angeles: The indexing syntax is the same for a cell array. You'd be dealing with an n-by-1 cell array rather than an n-by-1 column vector each time through the for loop.

[Michael Angeles]

Thank you for your help, I was able to get the program running.