Amend a column vector to a matrix array

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Christopher Arreola 2021-12-8

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评论： Christopher Arreola 2021-12-8

What are some simple ways to amend a column vector to an array? I am trying to avoid setting a fixed number of column vectors to an array and would rather amend column vector after column vector with a while loop until it reaches the end of the loop. Feel it would be unnecessary to fix the length of the array if this could happen and it would be more fluid

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Voss 2021-12-8

That will work. This also works:

w(:,end+1) = z;

It is a good idea to pre-allocate if possible, however, like Matt J points out in his answer.

Christopher Arreola 2021-12-8

hugh, well i'll take the increase in round off error if it provides a better matrix that fits my data set more accurately

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Answer 1

Matt J 2021-12-8

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编辑：Matt J 2021-12-8

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it would be unnecessary to fix the length of the array if this could happen and it would be more fluid

No, it won't be more fluid, because of

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

A compromise would be to hold the columns in a cell array and then combine them at the end, e.g.,

i=1;
c={};
while i<10
    c{i}=rand(4,1);
    i=i+1;
end
A=cell2mat(c)
A = 4×9
    0.4293    0.5831    0.1375    0.3251    0.9970    0.2210    0.0956    0.4595    0.1706
    0.9880    0.2839    0.6171    0.5244    0.4020    0.7433    0.8065    0.7895    0.0911
    0.7028    0.6208    0.9873    0.0436    0.8547    0.3176    0.0456    0.8947    0.7712
    0.5441    0.3587    0.6043    0.4594    0.0559    0.9560    0.8444    0.7481    0.7811