What does @m and m(:) signify here?

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Siddharth Behal 2021-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/1573008-what-does-m-and-m-signify-here

评论： Jaya 2021-10-27

cell2mat(cellfun(@(m)m(:),a,'uni',0))

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Answer 1

Star Strider 2021-10-27

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Correctly stated ‘@(m)’ is a function handle (see What is a Function Handle? for details) and the ‘m(:)’ forces the argument ‘m’ to be a column vector (see MATLAB Operators and Special Characters for those details), and since ‘m’ is obviously a cell array (that can contain anything, however here appears to be numeric) —

a = {randi(9, 1, 5)}                                            % Cell Row Vector
a = 1×1 cell array
    {[2 4 3 7 7]}
out = cell2mat(cellfun(@(m)m(:),a,'uni',0))                     % Array Column Vector Result
out = 5×1
     2
     4
     3
     7
     7

Experiment to get diferent results.

.

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Jaya 2021-10-27

Ah yes, function handle! I just forgot the word and was trying to explain in my own terms.

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Answer 2

Jaya 2021-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/1573008-what-does-m-and-m-signify-here#answer_817948

编辑：Jaya 2021-10-27

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From what I know, @(m) specifies a function that which will be defined in terms of m. And what the function does i.e. the function description is m(:). The a is the data structure (whatever type it is) on which the the function will perform its action, m(:).

Using the above description you can take a look at the example below (from mathworks website) and make an analogy . Here the task is to extract first three characters from the str elements. Hope this helps!

str = ["Saturday","Sunday"]
str = 1×2 string array
    "Saturday"    "Sunday"
B = cellfun(@(x) x(1:3),str,'UniformOutput',false)
B = 1×2 cell array
    {'Sat'}    {'Sun'}