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Basic Question on Imported Data Size

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Ann on 6 May 2014
Commented: Tomas Jurena on 6 May 2014
Hi there! i'm a newbie in Matlab. I have 5x3000 size of imported data (5 row times 3000 data points). How can i change these data size to 1x15000 size (1 row times 15000 (4x3000+3000) data points? I know that I can use this command successfully: data=[data(1,:) data(2,:) data(3,:) data(4,:) data(5,:)]; but is there any short codes that can be used since I also have a big data size (30x3000). If I use the above command, I believe it will not be efficient in terms of command writing.


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Answers (2)

Chandrasekhar on 6 May 2014
Edited: Chandrasekhar on 6 May 2014
where A(3x5000) is the imported data


Ann on 6 May 2014
hi Akshata M. Thanks for your reply. I have tried use this command but it is not what I want. For example if I have these data: a =
1 4 7 10
2 5 8 11
3 6 9 12
then i applied b=reshape(a,1,12); the output will be:
b =
Columns 1 through 11
1 2 3 4 5 6 7 8 9 10 11
Column 12
However, the desired output that I wish to obtain should be arranged like this:
1 4 7 10 2 5 8 11 3 6 9
Please advice me on other suitable code. Thank you.
Tomas Jurena
Tomas Jurena on 6 May 2014
Just use transpose of the data matrix in reshape, i.e.
so in your example,
b = reshape(a',1,12)
produces the desired result
b =
1 4 7 10 2 5 8 11 3 6 9 12

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Rowan on 6 May 2014
the easiest way is to use matrix operations to rearrange the data. e.g. if you want to combine two 3 by 3 matrices, A and B, into a 6 by 3 matrix C (6 rows, 3 columns) you would have for example:
A = ones(3);B = ones(3)*2; (just to show the difference between matrices) then: C = [a;b], which would come out as: C = [1 1 1;1 1 1;1 1 1;2 2 2;2 2 2; 2 2 2]
using this method you can rearrange your imported data, like so: (we'll called the data imported D and the result after rearrangement matrix Dtest)
Dtest = [D(1,:) D(2,:) D(3,:) D(4,:) D(5,:)];
basically D(1,:) means all the data in the first row of matrix D so you just create a new matrix with all the rows of imported data in one line.

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Ann on 6 May 2014
Hi Rowan! Thanks for your respond.
Correct me if i'm wrong, from your statement above, I understand that the Dtest code is the only way to create a new matrix with all the rows of imported data in one line which is also the same code as I mention in my first post.
My problem is that I have too many rows in my data (more than 30 rows), so is there any shortcut code that I can use in order to get all rows of imported data in one line? Thank you.

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