GNU Octave Manual Version 3 by John W. Eaton, David Bateman, Søren Hauberg Paperback (6"x9"), 568 pages ISBN 095461206X RRP £24.95 ($39.95) |
6.2.1 Creating Cell Array
The introductory example showed how to create a cell array containing currently available variables. In many situations, however, it is useful to create a cell array and then fill it with data.
The cell
function returns a cell array of a given size, containing
empty matrices. This function is similar to to the zeros
function for creating new numerical arrays. The following example creates
a 2-by-2 cell array containing empty matrices
c = cell(2,2) => c = { [1,1] = [](0x0) [2,1] = [](0x0) [1,2] = [](0x0) [2,2] = [](0x0) }
Just like numerical arrays, cell arrays can be multidimensional. The
cell
function accepts any number of positive integers to describe
the size of the returned cell array. It is also possible to set the size
of the cell array through a vector of positive integers. In the
following example two cell arrays of equal size are created, and the size
of the first one is displayed
c1 = cell(3, 4, 5); c2 = cell( [3, 4, 5] ); size(c1) => ans = 3 4 5
As can be seen, the size
function also works for cell arrays. As
do the other functions describing the size of an object, such as
length
, numel
, rows
, and columns
.
As an alternative to creating empty cell arrays, and then filling them, it
is possible to convert numerical arrays into cell arrays using the
num2cell
and mat2cell
functions.
- Built-in Function: cell (x)
- Built-in Function: cell (n, m)
- Create a new cell array object. If invoked with a single scalar
argument,
cell
returns a square cell array with the dimension specified. If you supply two scalar arguments,cell
takes them to be the number of rows and columns. If given a vector with two elements,cell
uses the values of the elements as the number of rows and columns, respectively.
- Built-in Function: iscell (x)
- Return true if x is a cell array object. Otherwise, return false.
- Loadable Function: c = num2cell (m)
- Loadable Function: c = num2cell (m, d)
- Convert to matrix m into a cell array. If d is defined the
value c is of dimension 1 in this dimension and the elements of
m are placed in slices in c.
See also mat2cell
- Loadable Function: b = mat2cell (a, m, n)
- Loadable Function: b = mat2cell (a, d1, d2, ...)
- Loadable Function: b = mat2cell (a, r)
- Converts the matrix a to a cell array If a is 2-D, then
it is required that
sum (m) == size (a, 1)
andsum (n) == size (a, 2)
. Similarly, if a is a multi-dimensional and the number of dimensional arguments is equal to the dimensions of a, then it is required thatsum (di) == size (a, i)
.Given a single dimensional argument r, the other dimensional arguments are assumed to equal
size (a,i)
.An example of the use of mat2cell is
mat2cell (reshape(1:16,4,4),[3,1],[3,1]) => { [1,1] = 1 5 9 2 6 10 3 7 11 [2,1] = 4 8 12 [1,2] = 13 14 15 [2,2] = 16 }
See also num2cell, cell2mat
ISBN 095461206X | GNU Octave Manual Version 3 | See the print edition |