Separating and splitting table by numeric values and writing to multiple files

I have a single CSV with data uploaded from multiple IOT sensors (all within the same file), each device's row distinguished by a unique numeric ID. I convert this into a MATLAB table using the

readtable()

method. I can then organize the file by grouping device ID's separately by using the

sortrows()

method on the Device ID column.

However, how would I split the grouped devices into seperate tables? Currently I use the following algorithm:

for g = 1:numDevices %create a new file for each device type
    outputFileIndoorData1 = sprintf("C:\Users\Documents\duetTestFile%d",g);
    for h = 1:height(indoorDataSorted) %Iterate through entire CSV, splitting by device ID
        if strcmp(indoorDataSorted.device_id(h),deviceIDs(g,1)) 
            writelines(indoorDataSorted(h,1:17),outputFileIndoorData1); %Write to individual file specified
        end
    end
end 

This is extremely resource intensive, however. What could be a more efficient way separating each devices data into a different file?

[Image Analyst]

Please attach the output of sortrows as a variable in a .mat file so we can try things with it. Make it easy for people to help you, not hard.

In the meantime, see findgroups

[Farid Barak]

@Image Analyst The output is too big to paste here, and is irrelevant. I've already explained what is in the file, I only need to seperate the table now based on the (sorted) values of column n.

Answer 1

[dpb]

" split the grouped devices into seperate tables?"

The short answer is "you don't!"

Use the DeviceID variable as a <GroupingVariable> and rowfun or groupsummary and friends to operate on those by group.

If you make more tables or files instead, you've just compounded the problem of analysis by having to bring all those back in again as they're needed when you've already got them and all the tools are already builtin with the table data class -- use them.

[Farid Barak]

@dpb The groupsummary solved all of the problems I was having, thanks!

[dpb]

Glad to help -- and to introduce another to the wonders of grouping variables!! :)