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The introductory example (see Basic Usage of Cell Arrays) 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 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 multi-dimensional. 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 other functions describing the size of an object, such as length, numel, rows, and columns.
Create a new cell array object.
If invoked with a single scalar integer argument, return a square NxN cell array. If invoked with two or more scalar integer arguments, or a vector of integer values, return an array with the given dimensions.
See also: cellstr, mat2cell, num2cell, struct2cell.
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
, mat2cell
and cellslices
functions.
Convert the numeric matrix A to a cell array.
If dim is defined, the value C is of dimension 1 in this dimension and the elements of A are placed into C in slices. For example:
num2cell ([1,2;3,4]) ⇒ { [1,1] = 1 [2,1] = 3 [1,2] = 2 [2,2] = 4 } num2cell ([1,2;3,4],1) ⇒ { [1,1] = 1 3 [1,2] = 2 4 }
See also: mat2cell.
Convert the matrix A to a cell array.
If A is 2-D, then it is required that
sum (m) == size (A, 1)
and
sum (n) == size (A, 2)
. Similarly, if A is
multi-dimensional and the number of dimensional arguments is equal to the
dimensions of A, then it is required that
sum (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 }
Given an array x, this function produces a cell array of slices from the array determined by the index vectors lb, ub, for lower and upper bounds, respectively.
In other words, it is equivalent to the following code:
n = length (lb); sl = cell (1, n); for i = 1:length (lb) sl{i} = x(:,…,lb(i):ub(i),…,:); endfor
The position of the index is determined by dim. If not specified, slicing is done along the first non-singleton dimension.
See also: cell2mat, cellindexmat, cellfun.
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