How to add NaN values to a matrix?

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Yelitza Perez 2020-11-13

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https://ww2.mathworks.cn/matlabcentral/answers/647178-how-to-add-nan-values-to-a-matrix

评论： Cris LaPierre 2020-11-14

Hi, I need to add NaN values to two matrices. One is a 1x48000 and it needs to be 1x48449 and the other is 4x48000 and it needs to be 4x48449. How can I do that? I need to add these extra values because the 1x48000 matrix is beign concatinated with another matrix of size 1x48449. So I was thinking to add some NaN values or maybe substract the 449 extra values from the second matrix.

Can anyone help me understand this better? Thank you for any help you can provide.

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Answer 1

Cris LaPierre 2020-11-13

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Use the missing function.

% Define a 4x5 matrix
A=ones(4,5);
% Turn into a 4x9
A(:,end+1:9)=missing
A = 4×9
     1     1     1     1     1   NaN   NaN   NaN   NaN
     1     1     1     1     1   NaN   NaN   NaN   NaN
     1     1     1     1     1   NaN   NaN   NaN   NaN
     1     1     1     1     1   NaN   NaN   NaN   NaN
●

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Yelitza Perez 2020-11-14

Thank you! I like your answer. But how would this work if I already defined the matrix in a previous line? (I had to change the name because I have two matrices on my workspace with the same name)

Cris LaPierre 2020-11-14

That's what my code does. I first defined the matrix A, then I increased its size by adding NaNs.

It would appear you know the size of your matrices, so adapt the code I shared to increase the size of your smaller matrix so that it is the size of the larger one.

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Answer 2

Setsuna Yuuki. 2020-11-13

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https://ww2.mathworks.cn/matlabcentral/answers/647178-how-to-add-nan-values-to-a-matrix#answer_543988

编辑：Setsuna Yuuki. 2020-11-13

在 MATLAB Online 中打开

A = rand(1,48000) %Matrix of example (1x48000)
B = rand(1,48449) %Matrix of example (4x48449)
C = [A;B(1:48000)] %You can take the matrix values from 1 to 48000, and concatenate.

and

A = rand(4,48000) %Matrix of example (4x48000)
B = rand(4,48449) %Matrix of example (4x48449)
C = [A;B(1:4,1:48000)] %You can take the matrix values from 1 to 48000, and concatenate.

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Yelitza Perez 2020-11-14

Thanks for this answer! Would the 'rand' part generate random values on a 1x48000 matrix? Because my 1x48000 already have values. I don't want to overide them, I just want to add 449 NaN more values at the end so it could work when I concatenate it with my other 1x48449 matrix.

Sorry I am new at this.

Setsuna Yuuki. 2020-11-14

在 MATLAB Online 中打开

A and B are your matrix, rand is a method to create random data, but is only a example.

A; %your 1x48000 matrix 
B; %your 1x48449 matrix
C=[A B(1:48000)] %concatenate A matrix and B matrix, but only from element 1 to element 48000 of B matrix

This method removes values from matrix B does not add NaN in matrix A

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