finding data in a matrix

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Lilya
Lilya 2018-10-29
评论： Lilya 2018-10-29
Hi all,
I am in a trouble :( i do have a matrix of 251*28 that I want to extract the data by giving x and y values (columns(28) and rows(251)). ex
ineedX = find(Xgrid >= 12 & Xgrid <=60); % the extracted data
ineedY = find(Zgrid>= -75 & Zgrid <=-60); % the extracted data
the find command is not working when I want to apply the function as it gives a vector which I want the matrix.
any help? Thanks a lot!

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采纳的回答

Bruno Luong
Bruno Luong 2018-10-29
Depending on how your data is organized, (you did not tell if x is first index or second) after doing
ineedX = find(Xgrid >= 12 & Xgrid <=60); % the extracted INDEX
ineedY = find(Zgrid>= -75 & Zgrid <=-60); % the extracted INDEX
you should do
DataExtract = Data(ineedX,ineedY)
Where Data is your original matrix. Or the reverse in indexes if you have x in second dimension.

更多回答（1 个）

KSSV
KSSV 2018-10-29
A = rand(251,28) ;
A(251,28) % this gives you 251 row and 28 column
Read about logical indexing. Don't use find.It will be slow.
Also read about ind2sub and sub2ind.
  1 个评论
Lilya
Lilya 2018-10-29
Thank you so much KSSV.. ur answers are always very helpful

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