Change type of a structure field

I'm fairly new to Matlab, so this might be a simple question or one that just isn't possible. I have a bunch of data that was grabbed from a JSON file. For one particular field, there might have been one or more words in the JSON object for any given item. The problem is that the toolbox I used (JSONlab) made that field a character array if there was only one word, and a cell array if there were more than one word. I would like all of the fields for each item to be cell array, regardless of the number of words in that field. Is there a way to force character arrays to become cell arrays?

Here's what I've tried so far (data is a 1x6000 cell array with 5556 valid items):

for i = 1:5556
    item = data{1,i};
    categories = item.categories;
    if ischar(categories)
        item.categories = cellstr(categories);
    end
end

This doesn't have any compile/run-time issues, but it doesn't actually change anything. For example, if the only thing in categories is "Mexican", then it's still a character array afterwards.

Answer 1

[dpb]

Does this help?

>> data{1}={'this is stuff'};
>> data{2}='word'
data = 
  {1x1 cell}    'word'
>> iscell(data{2})
ans =
   0
>> iscell(data{1})
ans =
   1
>> data(2)={data(2)}
data = 
  {1x1 cell}    {1x1 cell}
>>

?

[Ben]

Yup, that did it, thanks.

[dpb]

BTW, note the following for the above initial data array--

>> isnt=~cellfun(@iscell,data);
>> data(isnt)={data(isnt)}
data = 
  {1x1 cell}    {1x1 cell}

May make your job a little simpler.