Next: Comma Separated Lists Generated from Structure Arrays, Up: Comma Separated Lists

#### 6.3.1 Comma Separated Lists Generated from Cell Arrays

As has been mentioned above (see Indexing Cell Arrays), elements of a cell array can be extracted into a comma separated list with the `{` and `}` operators. By surrounding this list with `[` and `]`, it can be concatenated into an array. For example:

         a = {1, [2, 3], 4, 5, 6};
         b = [a{1:4}]
              ⇒ b =
                  1   2   3   4

Similarly, it is possible to create a new cell array containing cell elements selected with `{}`. By surrounding the list with ‘`{`’ and ‘`}`’ a new cell array will be created, as the following example illustrates:

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

Furthermore, cell elements (accessed by `{}`) can be passed 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 individual arguments. The two calls to `printf` in the following example are identical but the latter is simpler and can handle cell arrays of an arbitrary size:

         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

If used on the left-hand side of an assignment, a comma separated list generated with `{}` can be assigned to. An example is

         in{1} = [10, 20, 30, 40, 50, 60, 70, 80, 90];
         in{2} = inf;
         in{3} = "last";
         in{4} = "first";
         out = cell (4, 1);
         [out{1:3}] = find (in{1 : 3});
         [out{4:6}] = find (in{[1, 2, 4]})
              ⇒ out =
                 {
                   [1,1] = 1
                   [2,1] = 9
                   [3,1] = 90
                   [4,1] = 1
                   [3,1] = 1
                   [4,1] = 10
                 }