How do I add an additional column to a cell array based on existing values in another column?

I have a cell array (x) of dimensions 900x2. Column 1 is a unique identifier; there are two possible values of the second column, either "1" or "2". I want to add a third column which I want to be "1" if Column 2 is "1" and "0" otherwise.

I had previously asked a similar question where there were strings instead of numbers in Column 2 and a strcmp function was used but I would like to know similar function regarding numbers.

Any help appreciated!

[Stephen Cobeldick]

Earlier question:

https://www.mathworks.com/matlabcentral/answers/465807-how-do-i-add-a-column-to-a-cell-array-based-on-existing-values-in-another-column

[Jan]

"1" is a string, '1' is a char or char vector, 1 is a number, either as single, double or an integer type. Instead of explaining the contents of the cell as text, prefer to use Matlab syntax, because then it is clear immediately:

x = {'asd', 1; ...
     'bsd', 0};
% And you want to get:
y = {'asd', 1, 0; ...
     'bsd', 0, 1};

Is this correct?

[nskel]

Yes, thanks! The second column contains integers.

Apologies!

... and yes that is the output I am looking for!

Answer 1

[Jan]

x = {'asd', 1; ...
     'bsd', 0};
x(:, 3) = num2cell(1 - cell2mat(x(:, 2)))

% or:
Value = {0, 1};
x(:, 3) = Value(2 - cell2mat(x(:, 2)))

This was one of the approaches for the char data:

Value  = {'1', '0'};
x(:,3) = Value(2 - strcmp(x(:, 2), 'A'));

Here you can use the values to create the index instead of strcmp, but the equivalence is clear.

Answer 2

[Stephen Cobeldick]

>> x = {'x1',1';'x2',2;'x3',1}
x = 
    'x1'    [1]
    'x2'    [2]
    'x3'    [1]
>> x(:,3) = {0};
>> x([x{:,2}]==1,3) = {1}
x = 
    'x1'    [1]    [1]
    'x2'    [2]    [0]
    'x3'    [1]    [1]

Answer 3

[Joel Handy]

Obviously replace myCellArray with whatever your array is called.

isTwo = cellfun(@(x) x == 2, myCellArray(:,2));
myCellArray(:,3) = num2cell(double(isTwo))

Alternatively

isTwo = [myCellArray{:,2}]' == 2;
myCellArray(:,3) = num2cell(double(isTwo));

I'm not sure which is faster off hand.