Creating a table from different sized vectors

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Emmanouil Barmpounakis
评论： ju.shu 2020-6-17
I have a number of vectors (x1,y1,x2,y2, etc) with different lengts and I want to extract them to a .csv containing all these. Specifically,
  • 1st column = x1 (289 rows)
  • 2nd column = y1 (289 rows)
  • 3rd column = x2 (300 rows)
  • 4th column = y2 (300 rows)
I try to use the horzcat but it does not work due to different size. Any ideas or solutions?
  1 个评论
Stephen23
Stephen23 2015-12-17
Rather than storing these in numbered variables these vectors should really be stored in a cell array. Then the task becomes a trivial loop with indexing to allocate the vectors into a proallcoated array.
Numbered variables are invariably a bad idea:
http://www.mathworks.com/matlabcentral/answers/196952-how-to-create-new-variables-in-batches-with-strcat

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采纳的回答

Renato Agurto
Renato Agurto 2015-12-17
Hi, you could try:
A = nan(no_of_columns, longest_array); % or zeros or whatever you want to fill the unused spaces
and then (or for example in a for loop):
A(1:length(x1),1) = x1;
A(1:length(y1),2) = y1;
...
I hope this is what you want
  1 个评论
ju.shu
ju.shu 2020-6-17
hey,
what if I have two columns each one of them 2xn (like 2x4012, and 2x9877) fo instance the columns represent points coordinates, how can I save the 2 columns in a table??
Thanks.

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更多回答（3 个）

the cyclist
the cyclist 2015-12-17
Depends on what you want to appear in the "empty" spot. You could use NaN. Then
M = [[x1; nan], [y1; nan], x2, y2]
and then export the matrix M.
the cyclist
the cyclist 2015-12-17
One possibility is to store them in a cell array first, in which case empty will be empty.
M = cell(300,4);
M(1:299,1) = num2cell(x1);
M(1:299,2) = num2cell(y1);
M(:,3) = num2cell(x2);
M(:,4) = num2cell(y2);
Image Analyst
Image Analyst 2015-12-17
I'd just use fprintf() and write it out manually.

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