How to define array without size and append values

Question

NoYeah 2020-4-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/517727-how-to-define-array-without-size-and-append-values

评论： NoYeah 2020-4-14

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

in C++, by using the vector API

we can create empty array and append values.

//for C++
    vector<float> v;
    
    v.push_back(2.3);
    v.push_back(3.1);
    v.push_back(4.5);
    

then we got

v[0]=2.3

v[1]=3.1

v[2]=4.5

How to implement that in Mathlab?

I have read the tutorial but it said the limited dimension is required when I want to create empty array

like

Array = int16.empty(5,0)

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Answer 1

Walter Roberson 2020-4-14

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/517727-how-to-define-array-without-size-and-append-values#answer_425943

在 MATLAB Online 中打开

Array = [];
Array(end+1,1) = 2.3;
Array(end+1,1) = 3.1;
Array(end+1,1) = 4.5;

Caution: this is not as efficient as if you can pre-allocate. Every time you add on to the end, MATLAB has to create a new internal version of the array with one more slot in it, and copy the values from the old array to the new array and put on the new value. MATLAB is weak on growing-in-place