Multiple table input issues

I have a script that reads multiple tables that contain columns such as "Light", "Temp", "Weight". Each row in these tables represents a "trigger", where the light level, temperature and weight are all recorded.

The script finds which hour contains the greatest number of "triggers" and assigns it to a variable. If you run the script, the variable "intlist" represents the hours with the greatest number of triggers for each table passed through the script.

My issue is, I would like to perform a further action and create an array for the interval where there is the most triggers in each table. I can accomplish this once, for the latest table that the script runs, but I cannot for the life of me get it to work for all the tables. The output I need would be 4 arrays, each listing the lightlevels corresponding the the rows within the interval of highest trigger number.

I believe there is something wrong with the way I structured this loop but I cannot figure out where it is going wrong.

I will attach the script and all 4 tables.

     [file_list,path_n] = uigetfile('.xlsx','MultiSelect','on');
    if iscell(file_list)==0
        file_list=(file_list);

    end
    for i=1:length(file_list)
        filename=file_list{i};
         T1 = readtable([path_n filename]);
         
         lidx = T1.Light<=4;
         T1.Light(lidx) = (NaN);



         Tt = [repmat(fix(now), size(T1,1), 1) + T1.Time];                
         T1.Time = datetime(Tt, 'ConvertFrom','datenum');                           
         T1.Trigger = ones(size(T1.Time));                                           
        
         TT1 = table2timetable(T1);                                                 
         TT1c = retime(TT1,'hourly','count');                                         
      
         [maxEvent,idx] = max(TT1c.Trigger);

         intlist(i)=idx;
        
     
             hourlist=hour(T1.Time)==idx;
       lightlevels=T1.Light(hourlist);
         
         
         
  
    end

Answer 1

[Voss]

Since lightlevels is a vector, and that vector might be different lengths for different files, it makes sense to store those vectors in a cell array and set one element of that cell array each time through the for loop.

[file_list,path_n] = uigetfile('.xlsx','MultiSelect','on');

if ~iscell(file_list)
    file_list = {file_list}; % use { } here, by the way
end

n_files = numel(file_list);

lightlevels = cell(1,n_files); % lightlevels is a cell array now
intlist = zeros(1,n_files);    % and intlist is a numeric array (in case you need it)

for i = 1:n_files
    
    T1 = readtable([path_n file_list{i}]);
    
    lidx = T1.Light<=4;
    T1.Light(lidx) = NaN;
    
    Tt = repmat(fix(now), size(T1,1), 1) + T1.Time;
    T1.Time = datetime(Tt, 'ConvertFrom','datenum');
    T1.Trigger = ones(size(T1.Time));
    
    TT1 = table2timetable(T1);
    TT1c = retime(TT1,'hourly','count');
    
    [maxEvent,idx] = max(TT1c.Trigger);
    
    intlist(i)=idx; % set the i-th element of intlist
    
    hourlist = hour(T1.Time)==idx;
    lightlevels{i} = T1.Light(hourlist); % set the i-th element of lightlevels
    
end

disp(lightlevels);

    {13×1 double}    {15×1 double}    {12×1 double}    {23×1 double}

lightlevels{1}

ans = 13×1

9 10 10 10 10 10 10 10 10 10

lightlevels{2}

ans = 15×1

10 10 10 10 10 10 10 10 10 10

[Pesach Nestlebaum]

This works! THANK YOU!!!

[Voss]

You're welcome!

Answer 2

[Geoff Hayes]

@Peder Axensten - try creating a cell array of the data that you wish to save (I'm assuming that each iteration could produce a different number of lightlevels. For example,

lightlevels = {};
for i=1:length(file_list)
    % code from above
    hourlist=hour(T1.Time)==idx;
    lightlevels{i} = T1.Light(hourlist);
end

[Pesach Nestlebaum]

Ok, it created a 1 x 4 cell, but only the 4th column is occupied with a lightlevel list. Column 1 - 3 are empty.