Using the C++ Math Library

Deleting Elements from a Cell Array

Cell arrays follow the same rules as numeric arrays and structure arrays for element deletion. You can delete a single element from a cell array, or an entire dimension element, for example, a row or column of a two-dimensional cell array or a row, column, or page of a three-dimensional cell array. In MATLAB, you delete elements by assigning [] to them. In the MATLAB C++ Math Library, you assign the null array.

Deleting a Single Element

In order to delete a single element from an array of any type, you must use one-dimensional indexing. Deleting a single element from a two-dimensional cell array collapses it into a vector cell array. For example, using one-dimensional indexing, N(2) refers to element (2,1) of N. Deleting the (2,1) element of N (the complex number 2-4i) produces a three-element cell array. In MATLAB you write N(2) = []. See the graphical representation of N on page 4-31.

You remove element (2,1) from N like this:

N(2) = empty();

Deleting an Entire Dimension

You can delete an entire dimension by using vector subscripting to delete a row or column of cells. Use parentheses within the indexing string to indicate that you are deleting the cells themselves.

N(2,colon()) = empty();

N(2,:) = [] performs the same operation in MATLAB.

Note    N.cell(2,colon()) = empty(); is an error, because the number of items on the right- and left-hand sides of the assignment operator is not the same. The MATLAB C++ Math Library does not do scalar expansion on cell arrays. If you want to set both cells in the second row of N to [], write N(2,colon()) = cellhcat(empty(), empty()), thereby assigning a 1-by-2 cell array to another 1-by-2 cell array.

Assigning Values to a Cell Array

Indexing into MATLAB Structure Arrays