# how to expand 2D array?

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roudan el 12 de Mzo. de 2021
Hi
I create an array with shape of (2, 4), now I'd like to expand the array by 2 times in rows and 2 times in columns so the shape of array will become (4, 8). The values in the original small array will be only copied into a big every 2 rows and every 2 columns. NaN will be used for other locations. For example:
Original array, the values are:
1 2 3 4
5 6 7 8
The new array will be:
1 NaN 2 NaN 3 NaN 4 NaN
NaN NaN NaN NaN NaN NaN NaN NaN
5 NaN 6 NaN 7 NaN 8 NaN
NaN NaN NaN NaN NaN NaN NaN NaN
Then, I'd like to do interpolation to fill NaN in the big array.
Anyone has ideas? Thanks
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David Hill el 12 de Mzo. de 2021
Your final matrix is 2x16 not 4x8. Show us the final matrix with the interpolation done that you want.

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Adam Danz el 12 de Mzo. de 2021
m = [1 2 3 4
5 6 7 8];
y = reshape([[m;nan(size(m))],nan(size(m,2))],2,[])
y = 2×16
1 NaN 2 NaN 3 NaN 4 NaN NaN NaN NaN NaN NaN NaN NaN NaN 5 NaN 6 NaN 7 NaN 8 NaN NaN NaN NaN NaN NaN NaN NaN NaN
Version 2 after question was updated,
y = reshape([reshape([m(:),nan(size(m(:)))]',size(m,1)*2,[]); nan(size(m).*[2,1])],4,[])
y = 4×8
1 NaN 2 NaN 3 NaN 4 NaN NaN NaN NaN NaN NaN NaN NaN NaN 5 NaN 6 NaN 7 NaN 8 NaN NaN NaN NaN NaN NaN NaN NaN NaN
See comment below for an unpacked version of the line above.
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roudan el 12 de Mzo. de 2021
Awesome Adam, you are so considerate to help me unpack each line of code for me to understand it. Thank you. I appreciate it.
Adam Danz el 12 de Mzo. de 2021
Thanks, Yongnuan Liu. Happy to help out.

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