cannot fill table with chars?

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Budding MATLAB Jockey 2020-5-24

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评论： Giuseppe Degan Di Dieco 2021-5-12

Hi I am having a pile of issues with the table features in matlab.

I can't figure out how to put a char array into a char variable of a table. I've been reading the table help files but Il'm missing something :(

x=[1;2;3];
y=[4;5;6];
T=table(x,y)
T =
  3×2 table
    x    y
    _    _
    1    4
    2    5
    3    6
>> T.words = repmat({''}, 3, 1);
>>  T(1,'words') = 'poop';
The number of table variables in an assignment must match.
 
>> T(1,3) = 'poop';
The number of table variables in an assignment must match.
 
>> T{1,3} = 'poop';
The value on the right-hand side of the assignment has the wrong width. The assignment requires a value whose width is 1.

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Stephen23 2020-5-24

编辑：Stephen23 2020-5-24

在 MATLAB Online 中打开

"...but Il'm missing something "

It isn't a character array. You defined it as a cell array of empty character vectors:

T.words = repmat({''}, 3, 1);

It is certainly possible to define words to be a character array:

>> T.words = char(nan(3,0))
T = 
    x    y    words
    _    _    _____
    1    4         
    2    5         
    3    6         
>> T.words(1,1:4) = 'boat'
T = 
    x    y    words
    _    _    _____
    1    4    boat 
    2    5         
    3    6         
>> size(T.words)
ans =
     3     4       

but that is likely to be useful only in some specific circumstances. I would imagine that most users would prefer a string array.

Giuseppe Degan Di Dieco 2021-5-12

Dear Stephen,

thanks for your tip, indeed the solution of using a string array is very good.

Best.

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Answer 1

Tommy 2020-5-24

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https://ww2.mathworks.cn/matlabcentral/answers/531758-cannot-fill-table-with-chars#answer_437368

在 MATLAB Online 中打开

x=[1;2;3];
y=[4;5;6];
T=table(x,y);
T.words = repmat({''}, 3, 1); % this creates a 3x1 cell array

After these lines, T.words is a cell array:

>> T.words
ans =
  3×1 cell array
    {0×0 char}
    {0×0 char}
    {0×0 char}

You can fill it like so:

T(1,'words') = {'a'};
T(2,3) = {'bcd'};
T{3,3} = {'e':'z'};
% alternatively,
T{3,3}{1} = 'e':'z';

Which results in this:

>> T
T =
  3×3 table
    x    y             words          
    _    _    ________________________
    1    4    'a'                     
    2    5    'bcd'                   
    3    6    'efghijklmnopqrstuvwxyz'