How to obtain and locate group of pixel value from .mat file

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Karthik M
Karthik M on 1 Oct 2021
Commented: Karthik M on 7 Oct 2021
Hi Folks,
I have extracted chlorophyll from nc file attached
chlor_a max value 93.9236, chlor_a min value 0.0373
To identify and locate the number of pixels and its values which falls in particular grid
For example - I need to classify with pixel value interval with respective Lat [0 30] , Lon[30 100] (row and column) as shown and save in .csv/ .xls
range
0 - 2
2 - 4
4 - 6
6 - 8
8 - 10
10 - to the max
Thanks in advance
Kindly help
regards

Accepted Answer

KSSV
KSSV on 1 Oct 2021
Edited: KSSV on 1 Oct 2021
Read about logical indexing. Let C be your data.
idx = C >= 0 & C < 2 ;
c02 = C(idx) ;
idx = C >= 2 & C < 4 ;
c24 = C(idx) ;
Also with the same indices you can get respective lon and lat.
  3 Comments
Karthik M
Karthik M on 7 Oct 2021
Thanks in advance
I could get the indexed position of the rows and columns of max / index value data with the below code
maxval=max(data(:));
[xmax,ymax]=find(data==maxval);
[ii,jj]=find(data >= 0 & data < 2);
but I need only the exact x and y location coordinates
I have classify the the pixel range according to my requirement as below
idx = data >= 0 & data< 2 ;
pix1 = data(idx);
idx = data >= 2 & data < 4 ;
pix2 = data(idx) ;
idx = iwant >= 4 & iwant < 6 ;
pix3 = data(idx) ;
idx = data >= 6 & data < 8 ;
pix4 = data(idx) ;
idx = data >= 8 & data < 10;
pix5 = data(idx);
idx = data >= 10 & data < 15 ;
pix6 = data(idx) ;
idx = data >= 15 & data < 20 ;
pix7 = data(idx) ;
idx= data >= 20 & data < 95;
pix8 = data(idx);
Kindly help to get the exact x, y position of the group data

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