### 7.2 Indexing Cell Arrays

As shown in the introductory example elements can be inserted from cell arrays using the ``{`' and ``}`' operators. Besides the change of operators, indexing works for cell arrays like for multidimensional arrays. As an example, all the rows of the first and third column of a cell array can be set to `0` with the following code

         c{:, [1, 3]} = 0;

Accessing values in a cell array is, however, different from the same operation for numerical arrays. Accessing a single element of a cell array is very similar to numerical arrays, for example

         element = c{1, 2};

This will, however, not work when accessing multiple elements of a cell array, because it might not be possible to represent all elements with a single variable as is the case with numerical arrays.

Accessing multiple elements of a cell array with the ``{`' and ``}`' operators will result in a comma-separated list of all the requested elements. This list can then be used anywhere where a comma-separated list is used, such as in the creation of a new numerical array or cell array, or be passed as arguments to a function. If all the accessed elements of a cell array are scalars or column vectors, they can be concatenated into a new column vector containing the elements, by surrounding the list with `[` and `]` as in the following example

         a = {1, [2, 3], 4};
         b = [a{:}]
              => b =
                  1   2   3   4

It is also possible to pass the accessed elements directly to a function. The list of elements from the cell array will be passed as an argument list to a given function as if it is called with the elements as arguments. The two calls to `printf` in the following example are identical but the latter is more simple and handles more situations

         c = {"GNU", "Octave", "is", "Free", "Software"};
         printf ("%s ", c{1}, c{2}, c{3}, c{4}, c{5});
              -| GNU Octave is Free Software
         printf ("%s ", c{:});
              -| GNU Octave is Free Software

Just like it is possible to create a numerical array from selected elements of a cell array, it is possible to create a new cell array containing the selected elements. By surrounding the list with ``{`' and ``}`' a new cell array will be created, like the following example illustrates

         a = {1, rand(2, 2), "three"};
         b = { a{ [1, 3] } }
              => b =
                  {
                    [1,1] =  1
                    [1,2] = three
                  }

This syntax is however a bit cumbersome, and since this is a common operation, it is possible to achieve the same using the ``(`' and ``)`' operators for indexing. When a cell array is indexed using the ``(`' and ``)`' operators a new cell array containing the selected elements. Using this syntax, the previous example can be simplified into the following

         a = {1, rand(2, 2), "three"};
         b = a( [1, 3] )
              => b =
                  {
                    [1,1] =  1
                    [1,2] = three
                  }