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    Cell Fun

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    Barath
    Cellfun applies a function to each element in one or more cell arrays. It calls the specified function once for each element, passing in the element. The outputs from all function calls are combined into one or more output arrays. Cellfun allows applying a function to the cells in parallel without explicit for loops. Optional parameters include specifying output handling and error handling functions.

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    Cell Fun

    Uploaded by

    Barath
    119 views5 pages
    Cellfun applies a function to each element in one or more cell arrays. It calls the specified function once for each element, passing in the element. The outputs from all function calls are combined into one or more output arrays. Cellfun allows applying a function to the cells in parallel without explicit for loops. Optional parameters include specifying output handling and error handling functions.

    Original Description:

    Functions of cell array in MATLAB

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    Cellfun applies a function to each element in one or more cell arrays. It calls the specified function once for each element, passing in the element. The outputs from all function calls are combined into one or more output arrays. Cellfun allows applying a function to the cells in parallel without explicit for loops. Optional parameters include specifying output handling and error handling functions.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    119 views5 pages

    Cell Fun

    Uploaded by

    Barath
    Cellfun applies a function to each element in one or more cell arrays. It calls the specified function once for each element, passing in the element. The outputs from all function calls are combined into one or more output arrays. Cellfun allows applying a function to the cells in parallel without explicit for loops. Optional parameters include specifying output handling and error handling functions.

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    cellfun

    Apply function to each cell in cell array

    Syntax
    [A1,...,Am] = cellfun(func,C1,...,Cn)
    [A1,...,Am] = cellfun(func,C1,...,Cn,Name,Value)

    Description
    [A1,...,Am] = cellfun(func,C1,...,Cn) calls the function specified by function
    handle func and passes elements from cell arrays C1,...,Cn, where n is the number of inputs to
    function func. Output arrays A1,...,Am, where m is the number of outputs from function func,
    contain the combined outputs from the function calls. The ith iteration corresponds to the
    syntax [A1(i),...,Am(i)] = func(C1{i},...,Cn{i}). The cellfun function does not perform
    the calls to function func in a specific order.
    [A1,...,Am] = cellfun(func,C1,...,Cn,Name,Value) calls function func with additional
    options specified by one or more Name,Value pair arguments. Possible values
    for Nameare 'UniformOutput' or 'ErrorHandler'.

    Input Arguments
    func Handle to a function that accepts n input arguments and returns m output arguments.

    If function func corresponds to more than one function file (that is, if func represents a set of overloaded functions),
    of the input arguments.

    Backward Compatibility
    C1,...,Cn Cell arrays that contain the n inputs required for function func. Each cell array must have the same dimensions.
    Name-Value Pair Arguments
    Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name
    and Value is the corresponding value. Name must appear inside single quotes (' '). You can
    specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

    'UniformOutput' Logical value, as follows:


    true Indicates that for all inputs, each output from function func is a scalar cell array, scalar structure, or a scalar v
    (1) The cellfun function combines the outputs in arrays A1,...,Am, where m is the number of function outp
    outputs.
    false Requests that the cellfun function combine the outputs into cell arrays A1,...,Am. The outputs of functi
    (0)

    Default: true
    'ErrorHandler' Handle to a function that catches any errors that occur when MATLAB attempts to execute function func. Define this
    function func.

    MATLAB calls the specified error-handling function with two input arguments:
    A structure with these fields:
    identifier Error identifier.

    message Error message text.


    index Linear index corresponding to the element of the input cell array at the time of the error.
    The set of input arguments to function func at the time of the error.

    Output Arguments
    A1,...,Am Arrays that collect the m outputs from function func. Each array A is the same size as each of the inputs C1,...,Cn

    Function func can return output arguments of different classes. However, if UniformOutput is true (the default)
    The individual outputs from function func must be scalar values (numeric, logical, or character), scalar structures, or
    The class of a particular output argument must be the same for each set of inputs. The class of the corresponding outpu

    Examples
    Compute the mean of each vector in cell array C.
    C = {1:10, [2; 4; 6], []};

    averages = cellfun(@mean, C)

    This code returns


    averages =
    5.5000 4.0000 NaN

    Compute the size of each array in C, created in the previous example.


    [nrows, ncols] = cellfun(@size, C)

    This code returns


    nrows =
    1 3 0
    ncols =
    10 1 0

    Create a cell array that contains character vectors, and abbreviate each of them to their first three
    characters. Because the output character vectors are nonscalar, set UniformOutput to false.
    days = {'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'};

    abbrev = cellfun(@(x) x(1:3), days, 'UniformOutput', false)

    The syntax @(x) creates an anonymous function. This code returns


    abbrev =
    'Mon' 'Tue' 'Wed' 'Thu' 'Fri'

    Compute the covariance between arrays in two cell arrays C and D. Because the covariance output
    is nonscalar, set UniformOutput to false.
    c1 = rand(5,1); c2 = rand(10,1); c3 = rand(15,1);
    d1 = rand(5,1); d2 = rand(10,1); d3 = rand(15,1);
    C = {c1, c2, c3};
    D = {d1, d2, d3};

    covCD = cellfun(@cov, C, D, 'UniformOutput', false)

    This code returns


    covCD =
    [2x2 double] [2x2 double] [2x2 double]

    Define and call a custom error handling function.


    function result = errorfun(S, varargin)
    warning(S.identifier, S.message);
    result = NaN;
    end

    A = {rand(3)};
    B = {rand(5)};
    AgtB = cellfun(@(x,y) x > y, A, B, 'ErrorHandler', @errorfun, ...
    'UniformOutput', false)

    Extended Capabilities
    Tall Arrays
    Calculate with arrays that have more rows than fit in memory.

    See Also
    arrayfun | cell2mat | spfun | splitapply | structfun

    Topics
    Anonymous Functions
    Create Function Handle
    Introduced before R2006a

    MATLAB Function Reference

    cellfun
    Apply a function to each element in a cell array
    Syntax

    D = cellfun('fname',C)
    D = cellfun('size',C,k)
    D = cellfun('isclass',C,classname)

    Description

    D = cellfun('fname',C) applies the function fname to the elements of the cell


    array C and returns the results in the double array D. Each element of D contains the
    value returned by fname for the corresponding element in C. The output array D is the
    same size as the cell array C.

    These functions are supported:

    Function Return Value


    isempty true for an empty cell element
    islogical true for a logical cell element
    isreal true for a real cell element
    length Length of the cell element
    ndims Number of dimensions of the cell element
    prodofsize Number of elements in the cell element

    D = cellfun('size',C,k) returns the size along the k-th dimension of each element
    of C.

    D = cellfun('isclass',C,'classname') returns true for each element of C that


    matches classname. This function syntax returns false for objects that are a subclass
    of classname.

    Limitations

    If the cell array contains objects, cellfun does not call overloaded versions of the
    function fname.

    Example

    Consider this 2-by-3 cell array:

    C{1,1} = [1 2; 4 5];
    C{1,2} = 'Name';
    C{1,3} = pi;
    C{2,1} = 2 + 4i;
    C{2,2} = 7;
    C{2,3} = magic(3);

    cellfun returns a 2-by-3 double array:

    D = cellfun('isreal',C)

    D =
    1 1 1
    0 1 1

    len = cellfun('length',C)

    len =
    2 4 1
    1 1 3

    isdbl = cellfun('isclass',C,'double')

    isdbl =
    1 0 1
    1 1 1

    See Also

    isempty, islogical, isreal, length, ndims, size

    celldisp cellplot

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