is it possible to convert iddata to cellstr

Dear matlab users,

Is it possible to convert iddata to cellstr? i tried following code but it dont works.

cellstr(num2str(data.y(:,1)))]; %

%data.y(:,1) has this form 1×1 cell array {500×1 double}

500×1 char array

'0.0833333'

' 0.166667'

' 0.25'

' 0.333333'

' 0.416667'

' 0.5'

' 0.583333'

' 0.666667'

' 0.75'

.........

in this format i want vector

Thank you very much

Answer 1

[Star Strider]

Another approach:

data = iddata(rand(1,10)', (0:9)', 0.1);                % Create ‘iddata’ Object
y = data.OutputData;                                    % Get ‘OutputData’ As Double Array
ycs = cellstr(num2str(y));                              % Convert To Cell Array Of Strings

[Ill ch]

Hello Star, Thank you for your reply. yes the same thing what you done in

data = iddata(rand(1,10)', (0:9)', 0.1);                % Create ‘iddata’ Object
y = data.OutputData;                                    % Get ‘OutputData’ As Double Array
ycs = cellstr(num2str(y));                              % Convert To Cell Array Of Strings

But In my case i have bunch of the data in cell array. I could not access directly

y = data.OutputData;                                    % Get ‘OutputData’ As Double Array
ycs = cellstr(num2str(y));      

As i have 1*38 cell array. Your code work for one single data vector but here i have problem to access the data. you can check attached file. Thank you in advanvce

y: 1×38 cell array   % there are 38 column vectors
  Columns 1 through 5
    {500×1×0 iddata}  
    

[Daniel M]

Your cells are empty.

[Ill ch]

Hello Daniel,

Thank you for your reply. No they are not empty. I can plot all 38 cells with same data which i attached.

try after loading: plot(y{1}) or any number till 38. you will get results

[Star Strider]

I disagree! (At least the first and last ones are not empty. I did not check the others.)

Try this:

D = load('Ill ch mydata.mat');
y = D.y_Out;

for k = 1:numel(y)
    ycs{k} = num2str(y{k}.OutputData);                  % Create Cell Strings
end

Check = [ycs{1}(1:5,:), ycs{end}(1:5,:)]                % Confirm Result (Delete Later)

producing:

Check =

  5×22 char array

    '   0.095621   0.060427'
    '   0.082729   0.073796'
    '   0.060678   0.074488'
    '   0.033146   0.065841'
    '  0.0034351   0.050947'

Noting that ‘ycs’ indicates ‘y cell string’.

I have no idea why you want them as strings. That makes them more difficult to work with.

[Ill ch]

Thank you very very very much. It works. In order to save in csv i wanted to have string.

[Daniel M]

Oh, I see. Didn't realize you had written your own class. Just saw the size of the cell. Glad it is solved.

[Star Strider]

@Ill ch — As always, my pleasure.

You can (and it is best to) leave them as numeric if you want to save them as a .csv file. The problem now is that saving them as strings to your .csv file creates the additional problem of converting them back to numeric data later, when the .csv file is read.

@Daniel M — Ill ch did not create the class. This is the nature of the output that the System Identification Toolbox iddata function produces.

[Daniel M]

Ah, I see. I don't have this toolbox and had never heard of it before. help iddata redirected me to help griddata

Answer 2

[Daniel M]

Close, but you need to access the contents of the cell array, not the entire cell array itself.

data.y(:,1) = {rand(500,1)};
output = cellstr(num2str(data.y{:,1}));

[Ill ch]

Thank you very much

[Daniel M]

If it's not working for you, can you say why? (Is there a specific error?) Could you also upload your data, I can take a look.

[Ill ch]

Hi Daniel,

Thank you very much for your reply. Your code is for particularly random values for it your code works. But in my case i have problem to access the contents from cell array. as looks below my data structure:

  Name                  Size             Bytes  Class    Attributes
  y                     1x38            342362  cell
  
  y =
  1×38 cell array
  Columns 1 through 5
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 6 through 10
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 11 through 15
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 16 through 20
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 21 through 25
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 26 through 30
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 31 through 35
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}
  Columns 36 through 38
    {500×1×0 iddata}    {500×1×0 iddata}    {500×1×0 iddata}

when i am using direct cellarray it doesnt work.

   cellstr(num2str(y{16}))
Error using num2str (line 53)
Input to num2str must be numeric.

could you please help me how to access the contents of the cell array, instead of the entire cell array itself.

Thank you very much in advance

[Daniel M]

500x1x0 means your arrays are empty. You don't have any data.

Answer 3

[Rajiv Singh]

From iddata object "data", you can fetch the data arrays as cells using:

y = pvget(data,'OutputData'); 

In your latest query, y is a cell array of iddata objects. Thus x1 = y{1} will return one iddata object. Then pvget(x1,'OutputData') will return the value of its "OutputData" property as a cell array.

Note that size of 500x1x0 for an iddata object means that the data has 500 samples, 1 output and no inputs signals. The size() operator is specialized (overridden) for iddata objects.