How to find these features for large number of data?

Dear People,

I have 80 datasheets, and within each datasheet I have 3 different group. In each group I have 400 measurements.

I have to measure the root mean square value, Standard deviation, skewness etc.

But I have not got a clue how to do it for these many data point.

I started by transforming each coloumn into an array ( transposed it) and then managed to get rms. But I am wondering if there is a more efficient way of doing it.

If you guys have any suggestions please let me know.

My code:

X = transpose(table2array( reachandretrieve00(:,3)));

r = rms(X)

I have attached one of my datasheets.

Answer 1

[Kevin Phung]

i'm not sure how you're storing each datasheet, but if they are all in cell arrays (1 x 80 cell array, where each cell array is a datasheet):

rms_val = [];
for i = 1:numel(datasheets) % for each datasheet
    for j = 1:size(datasheets{i},2) % for each column in each datasheet
        rms_val(i,j) = rms(datasheets{i}{:,j}) %for each datasheet, store rms value into a row vector 
    end
end

[Lala0099]

Thank You for your answer.

Can I ask you one more question? If I have a datase( where the variables are in 3 different coloumns) and I would like to filter the data in each coloumn, how do I call for each coloumn in the datasheet, without haveing to seaparate them into arrays manually?

I would really appreciate your help

Thank you

[Kevin Phung]

so datasheet{1}{:,2} accesses the first datasheet, and the second column.

i am not too sure what you mean by filtering, but lets say i want to grab all positive values from this column...then I would do:

datasheet{1}{:,2}(datasheet{1}{:,2} > 0)  %logical indexing 

note that the curly brackey notation is a means of accessing information within a cell array.

example:

a = {[1 2 3 4 5]}; % a is a 1x1 cell array
a{1}(a{1}>2) %this would give me 3 4 5

[Lala0099]

Thank you for helping me! It worked :)

[Kevin Phung]

youre welcome!