How to access data that are cells in cells?

Hello,

I have a variable that contains 931x1 cells and each cell contain 1x30 doubles. When I open the variable from workspace I see this: 1x1 cell 4x1 cell 4x1 cell and when I click on a cell I see 1x30 double How I can access these data? I tried with cat command but this create one cell array in which all cell are in one column and I want to a table 932x30. I tried also to access with {} but this take only the first cell and show it like [1x30 double]. How I could to acces all the cells?

Thank you very much for any help

Answer 1

[Guillaume]

If you indeed have a 931x1 cell array and each cell contains a 1x30 vector, then

m = vertcat(c{:}) %where c is your cell array

will work. If it doesn't then you need to give us the output of

size(c)
class(c{1})
size(c{1})

[Kelly Kyriakou]

vertcat creates a variable 3721x1 cell

size(c) = 931 1 class(c{1}) = cell size(c{1}) = 1 1

[Guillaume]

So, each cell of the cell array is itself a cell array. Assuming that each cell of the cell array is a 1x1 cell array of a 1x30 vector:

cc = vertcat(c{:});
m = vertcat(cc{:});

If not, what is

class(c{1}{1})
size(c{1}{1})

[Kelly Kyriakou]

It works but it shows again only the data of first row. class(c{1}{1}) = double size(c{1}{1}) = 1 30

[Guillaume]

Sorry, made a typo, wrote a 1 instead of :. Now corrected.

Basically, because you've got cell arrays wrapped into a cell array you need to expand twice, c{:} each time.

Ideally, you'd correct the code that generated that cell array to remove the double wrapping.

Answer 2

[Star Strider]

Without seeing your data, it’s not possible to give a definitive Answer.

However, you can do multiple subscript reference addressing with cells, for example:

D = A{1}{1}
D = A{1}(1)

You will have to experiment with your own data. The cell2mat function is also an option for you to consider.

[Kelly Kyriakou]

I used 'D = A{1}{1}' as you told me and indeed I accessed the data. In order to access all the rows I wrote a loop like this:

   for i= 1:numel(myData{row}),
        output = getmyDatacolumns{i}{i}
     end

but this actually shows only the last values of the loop. How I could have all the data? Concerning cell2mat I have already tried but it doesn't work.

[Star Strider]

If you want to put your cell array into a table, also consider the cell2table function. I don’t know if it would work with your data, but I’d give it a go.

Also, you need to subscript your ‘output’ variable or it will only contain the last values in your cell array.

Consider:

   for i= 1:numel(myData{row}),
       output(i) = getmyDatacolumns{i}{i};
   end

You will have to experiment with variations on this idea with your cell array (you may need to add an inner nested loop and a second index to ‘output’), since you have it and we don’t.

[Kelly Kyriakou]

If I use output(i) = getmyDatacolumns{i}{i} I get this error "Subscripted assignment dimension mismatch."

[Star Strider]

None of your data that I looked at in your (931x1) cell are numeric. The contents are all strings, and they appear to be data on different major highways in some nation (I don’t recognise the designations).

This code for instance:

D = load('Kelly Kyriakou matlab.mat');
Cell = D.myData;

VarNames = Cell{1}(1:5)
S2 = Cell{2}(1:5)
S3 = Cell{3}(1:5)

produces this output:

    VarNames = 
        'name'
        'link_id'
        'link_key'
        'speed_sensor_id'
        'count_sensor_id'

    S2 = 
        'A2'
        '1'
        '1_AB'
        ''
        ''

    S3 = 
        'A2'
        '1'
        '1_BA'
        ''
        ''

If you want to create a table with them you could do something like this:

T = table(S2,S3,'RowNames',VarNames)

T = 

                           S2        S3  
                         ______    ______

      name               'A2'      'A2'  
      link_id            '1'       '1'   
      link_key           '1_AB'    '1_BA'
      speed_sensor_id    ''        ''    
      count_sensor_id    ''        ''

The data in the individual subcells (that I called ‘S1’ and ‘S2’ here) are mostly different lengths, so I have no idea how to suggest you deal with them. The table function requires that they all be the same length.