How can I pad zeros to each column of a matrix?

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Luki 2016-12-27

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评论： Image Analyst 2016-12-27

I am given a matrix with t rows and n columns. I want to add zeros to each column. How can I achieve this? I was thinking about the padarray-command:

X_padded = padarray(X,[10000 0]);

But I think this yields a matrix X with only zeros added to it in column n=1.

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Answer 1

Stephen23 2016-12-27

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Here are two easy ways to add zeros onto a matrix:

>> mat = [1,2,3;4,5,6]
mat =
   1   2   3
   4   5   6
>> [mat;zeros(2,3)]
ans =
   1   2   3
   4   5   6
   0   0   0
   0   0   0
>> mat(5,1) = 0
mat =
   1   2   3
   4   5   6
   0   0   0
   0   0   0
   0   0   0

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Luki 2016-12-27

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allright, thx! There's one problem:

size(x) = 10000 1 41

so, I could do:

x_zeros = [x,1,zeros(100,41)]

But I'd rather get rid of the third dimension of x (the 1 depicted in size(x)). I know it's not a real 3rd dimension, because the "depth" of the matrix is just 1. But every other assignment in my code will only use two indices (for columns and rows). For x as it is right now, however, I need three indices. Can I delete that additional dimension?