How to pop the content of a matrix in a way like pop the content of a cell

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raym 2020-6-19

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评论： raym 2020-6-19

We know that the arguments of a function can be placed in a cell and call it like this:

aCell = {arg1,arg2,arg3};
myFunction(aCell{:});

Is there a way to do this for a vector instead?

I tried this way, but it does not work

aVector = [2 3 4 5];
myFun(aVector(:)) % this does not work, the argument is a column vector [2;3;4;5] instead.

Similarly,

aVec = [1 2 3];
aCell = {'d','dew',aVec(:)} % I would expect aCell is {'d','dew',1,2,3}, but it is {'d','dew',[1;2;3]}, 

Thanks.

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KSSV 2020-6-19

Try num2cell(aVec)

Stephen23 2020-6-19

编辑：Stephen23 2020-6-19

There is no way to do this with a numeric array (or a char array, logical array, etc.). The only ways to generate a comma-separated list (the proper name for what you are trying to do) are from a cell array or from a field of a structure:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

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Answer 1

Ameer Hamza 2020-6-19

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在 MATLAB Online 中打开

Madhan's answer already shows how to use num2cell. Following just show how can you avoid the creation of a temporary variable

v = [1 2 3];
myFun(struct('a', num2cell(v)).a)

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Ameer Hamza 2020-6-19

Timing will be higher because of the additional overhead of struct creation (num2cell() being equivalent in both cases). However, it is only a concern if the function myFun() is itself has very small execution time (in order of microseconds) or the number of input arguments is in millions. If timing is a primary considerations, then it will be faster to just take input as an array rather than splitting it into an argument list. The point about obfuscation seems valid.

raym 2020-6-19

This is what I really want! Thanks!

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Answer 2

madhan ravi 2020-6-19

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编辑：madhan ravi 2020-6-19

在 MATLAB Online 中打开

aVector = [2 3 4 5];
aVector = num2cell(aVector);
myFun(aVector{:}) % ;)

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Answer 3

Walter Roberson 2020-6-19

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No there is not.

You can num2cell the vector and assign that to a variable and do expansion on that.

There are ways to use auxiliary anonymous functions to do the num2cell for you, and even to do cell expansion on the result, but when you proceed that way, the MATLAB parser will not know that multiple outputs are required and will pull out only the first value.