Generate n-dimensional array: problem with 1D

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Xiaohan Du 2017-11-8

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https://ww2.mathworks.cn/matlabcentral/answers/365868-generate-n-dimensional-array-problem-with-1d

评论： Star Strider 2017-11-8

采纳的回答： Star Strider

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Hi all,

Imagine I'd like to generate random dimensional zeros matrix, I can do:

K>> zeros(2, 2)
ans =
     0     0
     0     0
K>> zeros(2, 2, 2)
ans(:,:,1) =
     0     0
     0     0
ans(:,:,2) =
     0     0
     0     0

and so on. However, for 1D case, I'll have to use:

K>> zeros(2, 1)
ans =
     0
     0

I cannot use zeros(2) directly, meaning I have to deal with 1D case separately. Any idea how to make it smarter?

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Answer 1

Star Strider 2017-11-8

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That is as ‘smart’ as it gets, since it cannot read your mind. If you already have a vector and you want a zeros vector to match it, you can use the size of the original vector (or any dimension array) to create it:

x = 1:2;
v = zeros(size(x));

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Xiaohan Du 2017-11-8

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For example, I know the dimension of the zeros matrix I'd create, say for 2D, it's

zeros(2, 3)

for 3D, it's

zeros(2, 3, 4)

for 4D, it's

zeros(2, 3, 4, 5)

but for 1D, if I want a 2-by-1 matrix, I cannot write

zeros(2)

because this gives me a 2-by-2 matrix. I'll have to write

zeros(2, 1)

I understand that zeros(2, 1) also exists in 2D, but it does not completely follow the rules for nD.

Star Strider 2017-11-8

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That is the default behaviour of the zeros function. You can always write your own single-argument function to create a column vector of zero elements:

myzeros = @(n) zeros(n,1);

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