Column Format in a Table when using writetable

Is there anyway to format certain columns in a table.

My table looks like this in the command window,

T =
  10×5 table
    count    FrameNumber      DT      DiffDT       Type    
    _____    ___________    ______    ______    ___________
      1           0              0         0    {'Start'  }
      2           0         211.99    211.99    {'Trigger'}
      3           1         304.85    92.857    {'Trigger'}
      4           2         397.93    93.082    {'Trigger'}
      5           3         489.56    91.628    {'Trigger'}
      6           4         575.42    85.855    {'Trigger'}
      7           5         674.97    99.555    {'Trigger'}
      8           6         762.02    87.047    {'Trigger'}
      9           7         852.58    90.566    {'Trigger'}
     10           8         1070.6    218.01    {'Stop'   }

But when i save it to file, its not quite aligned, Im assuming its because of the number of decimal points

count	FrameNumber	DT	DiffDT	Type
1	0	0	0	Start
2	0	211.992979049683	211.992979049683	Trigger
3	1	304.849863052368	92.8568840026855	Trigger
4	2	397.932291030884	93.0824279785156	Trigger
5	3	489.56036567688	91.6280746459961	Trigger
6	4	575.415849685669	85.8554840087891	Trigger
7	5	674.970626831055	99.5547771453857	Trigger
8	6	762.017250061035	87.0466232299805	Trigger
9	7	852.582931518555	90.5656814575195	Trigger
10	8	1070.59550285339	218.012571334839	Stop
    

I thought T.Columnformat would work but it doesn't

This is my code: (its from a video object event log)

       function [T,count]=EventsLogTable(app,vid)
              events = vid.EventLog;
              % events.Data
              % events.Type
              Type = {events.Type}.';
              Data = [events.Data];
              AbsTime = datetime(vertcat(Data.AbsTime));
              T0 = AbsTime(1); % same
              DT = milliseconds(AbsTime-T0);
              DiffDT=diff(DT);
              DiffDT=[0;DiffDT];    %Pad otherwise 1 less in length
              %DT.Format = 'mm:ss.SSSS';        % 'mm:ss.SSSS';
              count = (1:numel(events)).';
              FrameNumber = vertcat(Data.FrameNumber);
              T = table(count,FrameNumber,DT,DiffDT,Type);     
        end

And then I call this:

       [T,count]=EventsLogTable(app,vid);             
       writetable(T,'F:\Temp\TableT.txt','Delimiter','tab')

I have tried this to round the two columns I need to and its almost correct it.

       DT = round(DT,2)
       DiffDT = round(DiffDT,2)       

       count	FrameNumber	DT	DiffDT	Type
1	0	0	0	Start
2	0	168.4	168.4	Trigger
3	1	266.37	97.98	Trigger
4	2	356.95	90.58	Trigger
5	3	449.85	92.9	Trigger
6	4	655.42	205.56	Stop

How can I make the columns also have the same number of decimals i.e.

1	0	0	0	Start
2	0	168.40	168.40	Trigger
3	1	266.37	97.98	Trigger
4	2	356.95	90.58	Trigger
5	3	449.85	92.90	Trigger
6	4	655.42	205.56	Stop

Oh, and how to get the headings all over the columns correctly

[Walter Roberson]

How can I make the columns also have the same number of decimals i.e.

1 0 0 0 Start

2 0 168.40 168.40 Trigger

I would point out that the zeros there do not have the same number of decimal points as the 168.40

Answer 1

[Walter Roberson]

varfun calling compose specifying a character vector format (so getting out cell array of character vectors.)

Repeat as often as necessary for the different formats you want to apply to different columns. [] the columns together and index the result to reorder the columns as needed, ending up with a cell array of character vectors.

Now possibly pre-pend a header column.

Now use writecell

To make it explicit: there is no facility built into writetable() for specifying column format.

Answer 2

[Karan Singh]

Hi @Jason,

As Walter has already stated, "there is no facility built into writetable() for specifying column format", rest I also think that rounding off to a nearest decimal point would also not help.

I converted the numeric columns into strings using a function like "sprintf" or "num2str" with your desired format (for example, '%.2f' for two decimals). Once converted, I converted the table to the file, and the output has remained in the same format.

% Sample data (as in your command window output)
count = (1:10).';
FrameNumber = [0; 0; 1; 2; 3; 4; 5; 6; 7; 8];
DT = [0;
      211.992979049683;
      304.849863052368;
      397.932291030884;
      489.56036567688;
      575.415849685669;
      674.970626831055;
      762.017250061035;
      852.582931518555;
      1070.59550285339];
DiffDT = [0;
          211.992979049683;
          92.8568840026855;
          93.0824279785156;
          91.6280746459961;
          85.8554840087891;
          99.5547771453857;
          87.0466232299805;
          90.5656814575195;
          218.012571334839];
Type = {'Start'; 'Trigger'; 'Trigger'; 'Trigger'; 'Trigger'; ...
        'Trigger'; 'Trigger'; 'Trigger'; 'Trigger'; 'Stop'};
    
% Create the table
T = table(count, FrameNumber, DT, DiffDT, Type);

% Display the original table in the command window
disp('Original Table T:');

Original Table T:

disp(T);

    count    FrameNumber      DT      DiffDT       Type    
    _____    ___________    ______    ______    ___________

      1           0              0         0    {'Start'  }
      2           0         211.99    211.99    {'Trigger'}
      3           1         304.85    92.857    {'Trigger'}
      4           2         397.93    93.082    {'Trigger'}
      5           3         489.56    91.628    {'Trigger'}
      6           4         575.42    85.855    {'Trigger'}
      7           5         674.97    99.555    {'Trigger'}
      8           6         762.02    87.047    {'Trigger'}
      9           7         852.58    90.566    {'Trigger'}
     10           8         1070.6    218.01    {'Stop'   }

% Write the original table to a file using default formatting.
writetable(T, 'Table_Original.txt', 'Delimiter', '\t');
disp('Wrote file "Table_Original.txt" using default numeric formatting.');

Wrote file "Table_Original.txt" using default numeric formatting.

%% Modify numeric formatting for specific columns
% Since writetable does not let you specify a numeric format,
% we convert the numeric columns DT and DiffDT into strings with a fixed format.
T_modified = T;  % make a copy of the original table
T_modified.DT = cellstr(num2str(T_modified.DT, '%.2f'));      % fixed to 2 decimals
T_modified.DiffDT = cellstr(num2str(T_modified.DiffDT, '%.2f'));

% Display the modified table (now DT and DiffDT are strings)
disp('Modified Table T_modified:');

Modified Table T_modified:

disp(T_modified);

    count    FrameNumber        DT           DiffDT         Type    
    _____    ___________    ___________    __________    ___________

      1           0         {'   0.00'}    {'  0.00'}    {'Start'  }
      2           0         {' 211.99'}    {'211.99'}    {'Trigger'}
      3           1         {' 304.85'}    {' 92.86'}    {'Trigger'}
      4           2         {' 397.93'}    {' 93.08'}    {'Trigger'}
      5           3         {' 489.56'}    {' 91.63'}    {'Trigger'}
      6           4         {' 575.42'}    {' 85.86'}    {'Trigger'}
      7           5         {' 674.97'}    {' 99.55'}    {'Trigger'}
      8           6         {' 762.02'}    {' 87.05'}    {'Trigger'}
      9           7         {' 852.58'}    {' 90.57'}    {'Trigger'}
     10           8         {'1070.60'}    {'218.01'}    {'Stop'   }

% Write the modified table to a file.
writetable(T_modified, 'Table_Modified.txt', 'Delimiter', '\t');
disp('Wrote file "Table_Modified.txt" with DT and DiffDT formatted to 2 decimals.');

Wrote file "Table_Modified.txt" with DT and DiffDT formatted to 2 decimals.

Here is the output to the file too attached.

Karan