Assign multiple values to a cell array

Question

I have a cell array that is declared as follow :

testCellArray = cell(m, n);

In a script, I specify the value of each cell as follow :

for loop (ii)
    testCellArray{ii, 1} = str2num(value1{ii});
    testCellArray{ii, 2} = str2num(value2{ii});
    testCellArray{ii, 3} = str2num(value3{ii});
    testCellArray{ii, 4} = str2num(value4{ii});
    ...
    testCellArray{ii, n} = str2num(valuen{ii});
end

I'm unable to put this in one line (I'm pretty sure it is possible).

I've tried something like this :

testCellArray{ii, :} = deal(str2num(value1{ii}, value2{ii}, value3{ii}, value4{ii}, ..., valuen{ii}))

But it isn't working. I'm also not sure if I should use testCellArray{ii, :} or testCellArray(ii, :).

sebastian · Accepted Answer · 2013-12-03 21:41:33Z

3

The better way would probably be the use of str2double instead of str2num, since it also takes a cell-array as input.

Than you could arrange the assignments as follows, without the outer ii loop:

testCellArray(:,1) = num2cell(str2double(value1));
testCellArray(:,2) = num2cell(str2double(value2));
...
testCellArray(:,n) = num2cell(str2double(valuen));

And, if your variables are really named value1, value2 etc., I can't resist to recommend: Get rid of enumerated variable names and put things into a list, presumably a cell-array in this case.

If you really need/want to keep the loop, the proper version of your deal assignment would be:

[testCellArray{ii, :}] = deal(str2num(value1{ii}), str2num(value2{ii}), ..., str2num(valuen{ii}));

However, not knowing how large n is, putting this in one gigantic line instead of several shorter ones surely isn't good coding style.

edited Dec 3, 2013 at 21:41

answered Dec 3, 2013 at 21:36

sebastian

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m_power Over a year ago

Right now n = 16. And no, the variables are not really named value1, value2, ...etc.

Luis Mendo · Accepted Answer · 2013-12-03 22:14:14Z

2

Assuming value1, value2 etc are vertical cell arrays of strings:

testCellArray = num2cell([str2num(strvcat(value1{:})) str2num(strvcat(value2{:}))]);

Note that strvcat can handle strings witth different lengths.

Example:

>> value1 = {'1';'2';'3';'14'};
>> value2 = {'5';'6';'7';'182'};
>> testCellArray = num2cell([str2num(strvcat(value1{:})) str2num(strvcat(value2{:}))])

testCellArray = 

    [ 1]    [  5]
    [ 2]    [  6]
    [ 3]    [  7]
    [14]    [182]

It's much more convenient if all value1, value2 etc are lumped into a single 2D cell array, such as:

value = {'1'  '5'   '-1';
         '2'  '6'   '-2';
         '3'  '7'   '-3';
         '14' '182' '-4'}; %// arbitrary number of columns

That way you don't have to modify the code to accomodate a varying number of columns. Just use

testCellArray = num2cell(reshape(str2num(strvcat(value{:})), size(value)));

or equivalently

testCellArray = mat2cell(str2double(value), ones(1,size(value,1)), ones(1,size(value,2)) );

to obtain the result

testCellArray = 

    [ 1]    [  5]    [-1]
    [ 2]    [  6]    [-2]
    [ 3]    [  7]    [-3]
    [14]    [182]    [-4]

edited Dec 3, 2013 at 22:14

answered Dec 3, 2013 at 21:56

Luis Mendo

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1 Comment

m_power Over a year ago

The fact is that the lenght of value1, value2, ..., valuen are not the same. So I don't see how they could be put in a single 2D cell array.

user2987828 · Accepted Answer · 2013-12-03 21:52:38Z

1

Solution with only one instruction:

testCellArray = cellfun(@str2num, [value1(:),value2(:),value3(:),...
  ,valuen(:)],'UniformOutput',false));

If all value* are vectical vectors, you can take (:) out.

answered Dec 3, 2013 at 21:52

user2987828

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